This may be your problem. You're supposed to lean it out until the RPM's max out, and then RICHEN it up a bit which will reduce the RPM. In other words turn the needle to the right to close it until you hear the engine running at it's fastest RPM, and then back it out to the left just a bit. If you are tuning it rich, and then richer, it won't make much power.

Also agree with what everyone else says, get a trainer and someone to show you how to fly if you can.