Not the best, but
You have a good melody idea, but it's not very well put together. Try getting a more professional music program, instead of a MIDI synthesiser. (the Fruity Loops Studio 7 demo is free and has all of the functions except you can't save the song to work on later (you can export as MP3, WAV, or MIDI). there is no trial time limit either) Try keeping things on beat too, the notes were all over the place.