I have replaced the stark plug and now need to know how to adjust the air and fuel ratio screws. I can not get the thing to start.

1. Dump your old gas.
2. Fill tank with fresh gas that is properly mixed with the right 2 stroke additive (can get a small bottle at Home Depot. Make sure ratio is right as directed on the bottle).
3. Check your spark plug connection. I recently trouble sourced a problem to my spark plug that wasn't apparent at first - the ceramic around my spark plug was cracked. Also may want to pull the spark plug to make sure it is not corroded or fouled with oil build-up.
4. You may want to give the carb a shot of starter fluid (1 - 2 sec. spray into carb).
5. Set choke to full. Hand off throttle. Pull until motor starts or begins to start.
6. Set choke to half full. Hand off throttle. Pull until motor starts. Once started wait until it has warmed up before setting choke to run.