Ancou - I think this is great for someone just starting out. You are on a really good path. Beat 5 definitely needs a melody but the bassline and drums work pretty well together, I don't see anything wrong with them. Same thing with Beat 6. Melodies are probably one of the hardest things to create (for me anyway), I don't know what you're using to make your beats but find some dope samples and lay them over your drums and bass and you'll have some bangers before you know it.