You should be able to find the short sale application online if your bank has it posted. Often you can make an online profile and then search until you find it. If it isn't provided online you should be able to contact your mortgage company for the short sale guidelines and submission.
I agree with this other answer, that if you are considering a short sale it would be in your greater interest to get with a Realtor. Most of us do this full time and know the full in's and out's of the banks loss mitigation departments.