I suggest you learn how to swap monster animations first, since there is a lot more info here at the forums about changing monster animations. Changing character animations is pretty much the same thing. Information is spread in lots of threads, you will have to search for a bit 
Suggested readings are:
http://dynamic2.gamespy.com/~phrozenkeep/ubb/Forum38/HTML/000301.html
In this thread you will find a simple method I posted to change monster animations. If you want to keep it simple, without messing with hex-editing or with .cof files, than you might like this one (it requires a little patience though
).
This the first animation conversion tutorial we had, by Nefarius. You may find some useful info here as well:
http://dynamic2.gamespy.com/~phrozenkeep/ubb/Forum38/HTML/000123.html
As I said, there are lots of other threads with bits of information, search the forums if you don't understand something explained in the threads above. Ask here if you are still confused 
Things to keep in mind when heading to character animations:
- character's animations have 16 directions, not 8 like monsters do.
- you will find character animations in other folders, can't remember the path right now but should be easy to find.
Hope this helps.
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"Get me a balrog attack-1 hand-to-hand animation, and I want it yesterday, the paladin is almost here!" ---> DMA1HTH @ offset 0006A480h. - Myhrginoc