First off, set all adjustments to zero. Then program receiver and ESC to radio.
Sub Trim is to center the servo before you make any steering adjustments.
EPA - increase to the point where the steering reaches the maximun turn for left then adjust right the same way. Don't over increase because you will stress the servo saver and drain battery more than needed.
EXP - usaully decrease to make steering less sensitive when you first start to turn the steering wheel. When going down the straight it is not so touchy at high speed (easier to drive). Decrease (-) on tracks with long straight, increase (+) on tracks with short straight.
Go to www.rcdocuments.com
and download the owner's manual for free.
Hope this helps. If you need more help let me know.