Congrats on taking action Mike.
Short sales can be a very tricky transaction if you are new.
It's hard to distill all of the nuances of a short sale transaction into a forum post, but it all boils down to the BPO (Broker Price Opinion). Basically, once you've submitted your offer to the lender, they are going to send out a real estate agent to do an independent appraisal of the property and come up with a figure for how much they will accept based on the value on the BPO. If that number is low enough to wholesale it or sell it to a retail buyer then you're golden.
You're going to need to put a COMPLETE short sale package together for the bank including a P&S agreement, Authorization to Release, Financial Statements and 2 years of the seller's tax returns along with a hardship letter explaining the reason for the default. The process can take 30 days up to a whole YEAR depending on who the lender is. I actually just closed on a SS with BoA that took 18 months! They are actually getting quicker at issuing approvals in my experience.
If you are attempting your first short sale, I suggest you find a SS negotiator who is familiar with the process rather than attempt to do it all yourself.
I don't like to do SS anymore these days because of the length of time involved, but that's just my preference. I outsource these types of deals to other SS investors in my area who want to work them in exchange for a percentage of the profits.
There are 3 "gurus" who specialize in this niche and if you do some research on google you should be able to locate their courses. Namely, Nathan Jurewicz, Cory Boatright and DC Fawcett.
Hope this puts you in the right direction.