DK's looking for info on how to play their class should start
here.
There are many different threads on a many different DK topics and specs. There is a lot of theorycraft there and a lot of people that have already done (most of) the work for you.
Note that not all of the threads are maintained by the same people, so you may need to dig through some forum posts for the best and most up-to-date info rather than just checking the first post.
If you have any questions beyond that, need help with rotations, or want some pointers, let me know and I would be happy to help you out one on one or at least point you in the right direction so you can find the knowledge yourself.
I know that I am not typically on during non-raid nights, but I can make myself available on those days if you let me know beforehand.
Aside from all of that, don't be afraid to drop some gold on respecs and test things for yourself if you have doubts about what you have read or been told.
