how do u pick your class…
sorry
Hit L to go into the Limbo menu, then click on the Allies or Axis symbol to join a team (the green symbol beside them is spectator). Then below that, click on the class you want.
The helmet means Soldier, the bullet means Field Ops, the wrench is Engineer, the crosshair is Covert Ops, and the + is Medic.
The numbers below each team/class symbol show the players in each team/class (for class, its just for your team).
To select a different weapon, click on the 2 that is beside a gun, and then click on a different gun. Not all classes have different guns.
Majin covered the question that you asked but I am going to also suggest that you read through the manual before playing. Even if you have experience with RtCW or similar games it will head off some other noob questions that may arise. You may also get some good ideas on how to play well from this website. If you already have experience with RtCW and similar games then your transition to ET should be pretty smooth. Have fun and see you in the games!
Dawg
p.s. the manual is included in the download.