Well. I have been working on a new tune, its sound really cool, but I´m in the melody part before the drop (Breakdown I think) but I need more back sounds to the melody

, also I have been listening another tracks and having ideas like bass lines, chords, long sweeps...so...
Can anyone give me some tips about putting chords into a melody?
How I can start it?
How you make your chords?

Thanks for replies

Sorry about bad grammar, not my language
