Guild Wars 2

So I haven’t played this game yet, but all my friends are playing on Tarnished Coast… Which is currently full. Am I never going to be able to play with my friends?

Except for WvW you can play with them regardless of which server you choose as long as it is an Na-Server. You just need to form a party with them.
If you wish to go to the world that another party member is in, right click on their portrait and choose Join In, and you will be moved to their world.