I’ve been trying for some time to do it myself but I just got into this music theory business and I kinda rely on guesswork and I just can’t figure it out.
If anyone could give me some pointers (key, scale, etc.) I hope to be able to figure it out <3
Cheers,
Adrie
In A major: A, E/G#, F#m, Esus4, D(add9), A
(I, V6, vi, Vsus4, IV(add9), I)
Awesome, thank you so much for your reply! This helps me so much!!
Now I’m working on the melody and the lead that sit on top.
Does this sound right?
http://www.hooktheory.com/hookpad/view/v-8H46YXPjfx
Cheers! 
Looks good to me. Only a couple of really minor edits I’d make:
For the top voice, I’m pretty sure the F# in bar 2 should be moved up to A, and the last three notes in Bar 4 should each be moved up a step (so it’s F#, G#, A).
For the lower voice, in bar 3 F# should be E, and the last note in bar 4 should be D.
Same goes for the repetition in bars 5-8. Hope that helps.