So what can I do if my friends have been playing for a while and I am brand new to the game and there server is full. how can I join thme
Servers are only of importance for WvW. The entire PvE side of this game runs on megaservers and every player can play with every other player. The only restriction here are regions, which are divided into EU and NA and allow only play between players of the same region.
As far as WvW is concerned, if the server your friends are on is full, you can join or transfer to the linked server given that one is not full (if there is a link server for this matchup). If there is no link server or the link is also full, you are out of luck for this matchup as far as WvW is concerned (again, nor PvE related). Links change every 2 months when they are reshuffled.