Your question isn't clear--do you want to know how to finger or play unfamiliar chords, or are you asking how ones goes about figuring out what the chords to the song are when you don't know them?

If you want to know how to figure out chord progressions, it makes a lot of difference what songs you are trying to figure out. It also depends on how much playing you have done. Most folk stuff is easy enough to follow by ear, if, as Sorcha points out, you know the key. A lot of pop and rock stuff is just as easy to follow--even a fair amount of the old time jazz stuff is easy to follow, if you know the circle of fifths--

The most important thing, when figuring out chords, is to make sure that you have the melody down, dead to rights--then pick your key and go to it. The melody usually follows the chord form--where you have a problem finding a chord, simply play the melody note, find a bass note that goes with it, and drop in the note a third above it--if that doesn't work, try a minor third below--you should be pretty close now--

If you are still having trouble, simply make a list of all the chords that use that note and try them all. If you still can't find the chord, go back and check to make sure you've got the melody note right.

Also, keep in mind that the chord changes tend to occur on strong beats, which would be the first and third count in 4/4 time, meaning that the chord on the second beat is going to be the same as the chord on the first beat, and the chord on the fourth beat is going to be the same as the chord on the third beat, even if the notes aren't in the chord--


Even though I will probably get clobbered for saying this, the truth is thatyou can work out simple chording if you just write out the melody and pencil some notes in following basic harmony rules--and you won't have to listen to a recording over and over again to do it.