I wanted someone to yeild but they rufused. So I entered the console and typed in "Yeild" Nothing happened.... What is the command supposed to do?

Sorry if this is the wrong forum.

P.S Your going to die in here, imperial. Your Going to Die!

As far as I understood it, if you're befriended with someone and you accidentally hit this one, during the fight then you can yield to "give up" so he won't kill you. It's a bit tricky though and totally depends on aggression against disposition, so only "friendly" NPCs have even a chance to accept your yield. Of course during the fight the particular NPC's disposition towards you might drop and aggression against raise, so it's becoming more difficult to have success with a yield.

What the actual command is supposed to do though, I don't know.

When called on an NPC it is intended to both stop combat and stop the alarmed state on the actor. If there are other actors in combat who are friendly to either party, they will also stop combat (which can make it more useful than calling stopcombat on each actor individually). However, if the actor is naturally hostile, or has a very low disposition toward the target due to being hit too much, they may begin combat again.

The reason why it might not have worked is because you did not select the actor in console.

Nah... I tried doing it... Near end of the game.

If you tried to Yield normally the game checks to see if that actor likes you enough to stop attacking. In your case they did not and carried on attacking.
When you use it in the console or in a script it does exactly the same thing, only via a direct command through the console/script. The actor still didn't like you enough to stop attacking so they carried on. What would have been unexpected is if they had actually yielded.

Note: As mentioned above, how much they like you is dependant on the NPCs base Agressiveness, and their Disposition towards you.