Disarm Macro

I've been having problems trying to create this macro. I'm able to do a few but still in the learning process. Would anyone please be able to show me how to create a Macro that would switch from one stance, to Defensive Stance, use Disarm, then hop back into my previous stance?

a macro can't tell what your previous stance was - assuming its zerker stance this will work:

#showtooltip Disarm
/cast [nostance:2] Defensive Stance; Disarm
/cast [stance:2] Berserker Stance

Thanks! Yeah, been playing WoW for a very long time but I never got into Macros for some reason. Now, though, since I am getting into heavy pvp I find them to be a huge lifesaver. Thanks for the help and I will continue to try and learn how to write them. :)