I have tried many times ive done everything all i do is fractures or i break something of mine off so if anyone can help me it would be appreiated if you can teach me that would be great.

I suggest turning off fractures, it removes the chance of getting a fracture and possibly increases the chance of attaining a DM, or you can play a mod with a low DM threshold, for example, mushu, judo ect.

Try to hit a joint (directly) with a lot of force. Use the speed meter to see what your top speed is when you are doing a kick or a punch.
Low speed kicks/punches usual do not dismember a body part.
To make dismembering bodyparts easier, lower the dm threshold. But be aware that this also makes it easier to get dismembered.

It depends on the mod.

http://forum.toribash.com/showthread.php?t=494249

Good tutorial ^

In my experience, hitting a joint directly coming from a direction in which doesn't flow with the joint with enough force should dismember it. For example: Hitting a fully extended elbow from above with sufficient force should break it, however if you hit it from behind, it will only fracture/break it.