It sounds as if you have already made another thread about this but I will go ahead and answer on this one.
You may not be getting spark, try taking out the spark plug and putting it in the spark plug wire and then grounding it to a part of the cylinder head that is not painted. Then have someone else turn over the engine while you watch the spark plug and see if a blue spark jumps the gap of the spark plug. If not you have an electrical problem. If you do get spark that is fine.
Then pour some gas into the spark plug hole (just a small amount) and see if it fires a couple times, that means it is a fuel problem. Make sure there is no kinks in your fuel line.
Usually even if the carburetor is not tuned correctly it will still fire up, just run really rough or may not idle well. But here is how to clean it, and then if it runs I will tell you how to tune it.
Take the carburetor off and spray everything down with carburetor cleaner. Especially the main jet and pilot jet, spray in those really well until you see carb fluid draining out the other side of them (into the venturi of the carburetor, or the middle of the carburetor tube, however you want to say that.)
Next take off the float and needle, and spray carb cleaner really well into the chamber where the needle sits. If there is an excess amount of gunk at the top of the chamber, fuel may not be going in (it will definitely not come in if there is something blocking the needle seat (the little ring the needle sits in.)
Then while the float is off bend the tange on the float itself so when the carburetor is upside down and the float has been once again placed on the carburetor that the float sits parallel to the carburetor body.