If your engine is to lean a way to check it is to:
1) Start it
2) Run it wide open
3) While on full throttle take and hold your plane nose up in the air. Your engine will quit if it is to lean.
To adjust your mixture you would :
4) Re-start engnie
5) Run it on wide open
6) Then adjust the needle valve usually away from you
7) Repeat steps 1-3