you need to master your songs. press f9 when you're in FL. that shows the different channels to master in. when you click on an instruments title when they're in the "box", a small little window pops up. in the upper right hand corner of that window there is a little digital number thing. click and drag to the desired mastering channel. hopefully that will help you with the quality.
but you really need to work on the notes. these are basic notes and they get boring.