Theory question: translating notes into chords

How do you replace notes with chords and have them  sound right? Sometimes in putting together a song, I can get a musical phrase that's in my head down in terms of finding the notes on the fretboard, but when I try to replace those notes with chords (replacing an F note with an F major chord, etc.) it sounds far different, and often quite horrible. Anyone have any basic tips/rules on how to do this? Thanks.

uke5417

I came to this site with the exact question!!!  Please someone answer it!

Thanks.

jbs