if I come up with a melody but want it to be chords, how do I play it?
 

If I come up with a melody in my head but want it to be chords, how do I play it on my guitar? There's always 1 note that stands out in a chord. When you hear a song and sing along, you sing that note. How do you find out which chords have that specific note stand out that you want, so you can find out which chord fits what you want? Also, how do you know which tuning to use?. The only obvious ones to find are powerchords, but aside from that i'm not sure how to do it.

That's a loaded question because there can be different chord combinations that can work with any one melody.

The best thing to do is find the key of your melody and use chords based out of that key. Knowing music theory goes a LOOONG way here (especially if your melody will dictate the use of an "accidental" which is a chord that doesn't make diatonic sense with the key -- and this happens a LOT in music)

I just do what Rexx said, I make a melody in a certain key then match the chords up with that key