how do i use this

hi folks first id like to thank everyone for bringing this game back to a modern state secondly im having a hard time assigning the keys on my joystick to lock and fire weapons and the guns i use the very easyest setting so it should be switch to weapon system lock close in and fire right but i cant figure out what locks my target and i use the hat switch to move my targeting curser but cant get it to lock on i dont even know what button would lock it for me please help and keep it really simple for me please cause in 2009 i was hit by an ied in iraq and i have some brain damage so if its to complicated i will prob have to bug you alot cause ill have a hard time following you sorry for any inconvence i may cause you ahead of time and thanks again