how to make a gui for a fps game

I am looking to make a gui for the map I made and with unity can I make a gui so when this is started up you can create a room to join for each map I have?

Unity’s OnGUI is very quick to start with but it sucks both feature wise and performance wise. I would suggest you use NGUI (not free) or wait for Unity 4.0 new GUI system.

They already said that the new GUI will not be available before 4.1 though.