The most simple way to learn melody is to put a pick on your thumb and one on either your middle or index finger and do a sort of 'squeeze', bringing the finger toward the thumb...which causes the thumb to move a bit toward the finger, as you play the chords. If you reach higher or lower as the tune/notes demands and 'think' the melody, you will suddenly hear the melody...along with other notes-- but IF the melody note is in the chord..especially if you hit it early in the strum, the mind picks the melody out of the other notes.

With practice, you can control this process pretty exactly, and add more picks..(if you wish...I seldom do)....there are various ways to proceed from there, like 'back-strumming' (making the finger go both ways...usually using a special pick, though I can do it with just plastic..)....this is similar to the process used by Kilby Snow, though he had the 'harp flat on a table..If you hold it to your chest, as is common these days, it is even easier.

It is very hard to NOT play the melody in my opinion, unless you just strum 'glissandos' across all the strings...

have fun!