Resolved Question

I have played guitar off and on for a while (not that Im any good) and have recently taken an interest in writing my own material. not for fortune, just for my own expression and peace of mind. but every time i try to transpose my mood/emotions/feelings into chords and onto the fretboard, i can never find the right chords to express what Im feeling in my head. any songwriters out there got any suggestions?

The simplest way to do it is happy/upbeat songs are set in a major key and sad/angry songs are set in a minor key. Of course this doesn't mean every chord in the song is major or minor, but pick a key you like and pick either the major or minor mode to correspond with the emotion you want to convey.

Of course, you can be much more creative and complex than that if you want to be, but you asked for the simplest way. :) Other options:
-- Suspensions can add tension, while resolution of a suspension can bring relief or a feeling of closure
-- Deceptive cadences can add a mysterious or unexpected type feeling
-- Half cadence can be used somewhat like a comma -- in other words, put a break in your musical sentence

There is more... I just can't think of it off the top of my head. Hope this helps though. :)