steering levers

Mower "jumps and bucks" when I push levers forward. What needs to be adjusted?

I need step by step instructions for adjusting tracking. Mower was drifting to the left, and couldn't remember how a friend that works on lawnmowers showed me to do it. At one point, it just got to where it would make a circle, and when I put it in Park, it was still trying to go. With the...