CTF has a few different play rules..just be sure to listen to the ref explaining the rules...
hand signs? I assume when you are hit you put your hand up
sometimes it's you have to defend your flag and try to capture theirs. Which is true for both teams.
It could also be that there is only one flag at the centre of the map, that both teams are trying to capture. (personally think this one is crap, because no matter how long you defended the flag, if they get it the last second, they win)