Ok this is an old-ish post but I'm bored I'm hoping this might be of some use to you if you're quite new to music and music theory. Sorry if you already know this!!
Exactly what Jim622 said, familiarise yourself with chord structures for keys and that's a really good way to start because a lot of popular songs don't deviate from their home key and so harmonically follow the same chord structure throughout.
Let's use C as our example as it's easiest. For the C Major scale, your chords are:
C | Dm | Em | F | G | Am | Bdim
In most cases, if it's a minor song then it's likely that the minor chord structures of that key are exactly equivalent to what is called the "relative major" of that key. To find the relative major of a minor key, go UP three semitones (three frets on a guitar). Conversely, to find the relative MINOR of a major key, go DOWN three semitones. (The reason I say it's "likely" is that there are actually a few different minor keys. There are also different major keys too but the different minor keys more often yield different patterned chord structures. Another lesson, another time!)
So the relative minor of C Major, if we go down three semitones we get to (B, Bb and then) A, so it's A minor. And lo and behold A Minor has exactly the same chords as C Major. Same goes for D Major and B Minor, Ab Major and F, C# Major and Bb Minor (probably dicking on enharmonics with the last one there, I'm losing my attention to detail, don't hold it against me!). All of these pairs of keys have the same chord structures as each other and it's pretty much exactly the same chords as the ones I wrote out above but just shifted to a different key! (To illustrate that, the F Major chords are F | Gm | Am | Bb | C | Dm | Edim, same pattern just different pitches!)
The basics of music lies with THESE CHORD PATTERNS. If you want to start experimenting with putting chords to your lyrics then these chords will get you started. Like I said, so many big dogs get by using only these kinds of chord patterns. The most commonly used chords are the First, Fourth, Fifth and Sixth (for C that is: C, F, G and Am).
This might be all stuff that you already know and I'm sorry if that's true!