I need help!!!!!!!

You mean the axel /cones get loose? Make sure your locknut is there and nothing is rubbing to loosen the axel.

Is this a coaster brake or cassette?

mine did that a lot then it kind of stopped. Get one of those bicycle wrenches that are flat hold the lock nut with it and turn the big one. Get them tight together.

My coaster brake hub does it alot also.

Unless there is crud or sand or ??? in there to really speed up the wear, nothing should loosen up if everything is tight and adjusted properly from the start. It is a bit tricky to get it right the first time sometimes and I know with a coaster brake you have to remove or grind down the dust cover one the engine sprocket side to clear the sprocket.

Better very slightly loose than too tight.