Look in the instruction manual for the controls and make sure you are familiar with how to direct and power your shots. Always aim for the corner of the goal, and either shoot with power to hit it...
Sorry m8 but it is impossible to do this on ps2 :-( i had the same problem. Diving is aviable only on new gen consoles :-/
While you are on the box, Press L1+L2+R1.
I think it helps