Very painful muted cords, I need help

I am brand new to guitar and find it very painful to play just about any cord. I also find it almost impossible to not mute adjacent strings, I have fat fingers.

Any tricks or exercised I could do would be appreciated.

You need to work on stretching and strengthening your fingers (in that order). An old guitar teacher of mine gave me this little stretching exercise as a starter:

E-1-|---|-3-|---|-4-|---|---|---|---|---|---|---|---
B---|---|---|---|---|---|---|---|---|---|---|---|---
G---|---|---|---|---|---|---|---|---|---|---|---|---
D---|---|---|---|---|---|---|---|---|---|---|---|---
A---|---|---|---|---|---|---|---|---|---|---|---|---
E---|---|---|---|---|---|---|---|---|---|---|---|---

The frets correspond to the frets on the guitar neck. The number on the fret represents the finger you should place on the designated fret. (index finger=1, middle finger=2, ring finger=3, pinky=4.)

Play the above pattern in this fashion starting on the 1st (or high E) string:

1 (hold for 4 beats), 3 (hold for 4 beats), 4(hold for 8 beats). Then back down: 4 (hold for 4 beats), 3(hold for 4 beats) 1 hold for 4 beats. Then repeat this pattern on the 2nd String, 3rd String, ....All the way down to the 6th (Low E) string. Make sure when you play the pattern that you keep your other fingers down on their respective frets (for example, when playing the note on the third fret with your 3rd finger, keep your first finger on the first fret. When playing the note on the 5th fret with your 4th finger, keep your 1st finger on the 1st fret, and your 3rd finger on the 3rd fret.

This exercise really starts to burn, especially as you get closer to the 6th (Low E) string. Keep at it and do it every day. Once you find that you are able to do the above exercise with relative ease, then there are variations of the above exercise which you can use to stretch and strengthen your fingers further. Some of the variations are:

1 - 2 - 4 (top number = finger)
1 - 3 - 5 (bottom # = fret)

1 - 2 - 3
1 - 3 - 5

1 - 3 - 4
1 - 4 - 7

1 - 2 - 4
1 - 4 - 7

1 - 3 - 4
1 - 4 - 8 (I think you get the idea....)

i'll tell you what I do. I take a tennis ball and wedge it between my index and middle finger, one between my middle and ring finger, and one between my ring finger and pinky. Then i sit for about ten minutes take them out for ten then put em back in. i do it about 2 times a day, like when I watch tv or whatever, it helps your fingers stretch and then it will get easier to reach. another reason chords may be muted is if you're holding the neck worng. you SHOULD NOT rest then neck between your thumb and index finger. your thumb should be half way down on the neck. when you do it this way, your fingers get much more reach.

Originally posted by paulbs
I have fat fingers.

That's all what my students say (a variation is 'my fingers are too short')That's what I said too. But you'll see you'll get used to it... Hang in there!! Enjoy....