You have to pay the people who own the satellites (Astra, owned by SES, a satellite-owning company) for a frequency. Then you can start broadcasting.
Then you buy a channel number from Sky if you want to be in the Sky Guide, and a channel number from FreeSat if you want to be in their TV Guide. You don't have to, but if you don't then no-one will watch you; people can put the specific frequency into their boxes as an "other channel", but effectively no-one does.
You can choose to broadcast entirely unencrypted, in which case anyone able to pick up the signal can watch (which will include much of western Europe), or you can use the basic encryption used by ITV on FreeSat which prevents it being watched through a non-UK satellite box. This has the advantage that if you license some content, then you only need a UK license (the BBC pays more for a film than ITV does for the same film because people in France and Spain and Portugal and Ireland can watch the film if it's on BBC and they can't if it's on ITV), it has the disadvantage that it stops (some of) the expat communities watching, which reduces your audience. In practice, a lot of expats have extra cards and things so they can watch UK TV, but certainly a lot less than can watch if it's unencrypted.
Alternatively, you can use the full Sky encryption system, which you have to pay Sky for. If you do this, then your channel is only available to people who have paid for the relevant package - but you will get paid a carriage fee depending on the number of subscribers. A typical example of a channel like this is Sky One or Discovery. Alternatively, you can have the channel outside of the bundle as a premium channel - that means you don't negotiate carriage fees, you just get paid the amount people pay in subscriptions, less a percentage taken by Sky for access to their encryption system. That's how Sky Sports works, but also BT Sport on Sky.
Virgin (ie cable) works basically the same way as Sky, ie you pay to be on it, but you can choose to be in a channel package or to be a premium channel and then customers pay extra to watch you, and that money, less a cut for Virgin, gets paid back to you.
Then there's Freeview, which is run by DTV Services. If you're not a shareholder of DTV Services (that's BBC, ITV, Channel 4 and Sky) then you have to pay them to be broadcast and to have a channel number. There's no premium channel options on Freeview, obviously.
Then there's streaming on top, but they probably just do that themselves or do it via YouTube. They can either do it for free, or they could charge a subscription.
Net effect for GB News is that there are three options:
1. Free to air, which means they have to pay Astra, Sky, FreeSat, Virgin and Freeview for broadcast and channel numbers.
[The ITV option of encrypted free to air is pointless for them as they won't be paying nearly enough to buy in rights]
2. Basic package, which means they pay Astra, but Sky and Virgin pay them a carriage fee (amount to be negotiated) and they are not available elsewhere - except maybe as a paid online stream.
3. Premium channel, which means that only people who specifically subscribe can see it, probably with an arrangement so that those people can also access it on streaming as well.
The same options are available in the US, but far more people over there have a basic package from cable or satellite TV, so "basic cable" is a much more viable tier - that's where Fox News is, for example. GB News would limit their audience far too much by restricting the channel to Sky/Virgin (and online subscribers, probably NOW TV) so they have to go for the free to air option.
On the revenue thing.
On Satellite, it works like this:
You have to pay the people who own the satellites (Astra, owned by SES, a satellite-owning company) for a frequency. Then you can start broadcasting.
Then you buy a channel number from Sky if you want to be in the Sky Guide, and a channel number from FreeSat if you want to be in their TV Guide. You don't have to, but if you don't then no-one will watch you; people can put the specific frequency into their boxes as an "other channel", but effectively no-one does.
You can choose to broadcast entirely unencrypted, in which case anyone able to pick up the signal can watch (which will include much of western Europe), or you can use the basic encryption used by ITV on FreeSat which prevents it being watched through a non-UK satellite box. This has the advantage that if you license some content, then you only need a UK license (the BBC pays more for a film than ITV does for the same film because people in France and Spain and Portugal and Ireland can watch the film if it's on BBC and they can't if it's on ITV), it has the disadvantage that it stops (some of) the expat communities watching, which reduces your audience. In practice, a lot of expats have extra cards and things so they can watch UK TV, but certainly a lot less than can watch if it's unencrypted.
Alternatively, you can use the full Sky encryption system, which you have to pay Sky for. If you do this, then your channel is only available to people who have paid for the relevant package - but you will get paid a carriage fee depending on the number of subscribers. A typical example of a channel like this is Sky One or Discovery. Alternatively, you can have the channel outside of the bundle as a premium channel - that means you don't negotiate carriage fees, you just get paid the amount people pay in subscriptions, less a percentage taken by Sky for access to their encryption system. That's how Sky Sports works, but also BT Sport on Sky.
Virgin (ie cable) works basically the same way as Sky, ie you pay to be on it, but you can choose to be in a channel package or to be a premium channel and then customers pay extra to watch you, and that money, less a cut for Virgin, gets paid back to you.
Then there's Freeview, which is run by DTV Services. If you're not a shareholder of DTV Services (that's BBC, ITV, Channel 4 and Sky) then you have to pay them to be broadcast and to have a channel number. There's no premium channel options on Freeview, obviously.
Then there's streaming on top, but they probably just do that themselves or do it via YouTube. They can either do it for free, or they could charge a subscription.
Net effect for GB News is that there are three options:
1. Free to air, which means they have to pay Astra, Sky, FreeSat, Virgin and Freeview for broadcast and channel numbers.
[The ITV option of encrypted free to air is pointless for them as they won't be paying nearly enough to buy in rights]
2. Basic package, which means they pay Astra, but Sky and Virgin pay them a carriage fee (amount to be negotiated) and they are not available elsewhere - except maybe as a paid online stream.
3. Premium channel, which means that only people who specifically subscribe can see it, probably with an arrangement so that those people can also access it on streaming as well.
The same options are available in the US, but far more people over there have a basic package from cable or satellite TV, so "basic cable" is a much more viable tier - that's where Fox News is, for example. GB News would limit their audience far too much by restricting the channel to Sky/Virgin (and online subscribers, probably NOW TV) so they have to go for the free to air option.