When you start the wallet the first time you get 100 new keys (called the keypool).
When you solo mine, the wallet picks one of those and signs the block with it.
thank you. i left it run over night. no winner. no chicken dinner!

how can i calculate the odds of winning the block? i divide the difficulty by hash or something like that?
what do you estimate the odds are with a computer that hashes at 11k, or 5k

Uhh, unfortunately with 1300 miners, not very good. I can tell you with relative accuracy now that Ive left my 3 miners on for a couple months 24/7, I usually earn about 550 BBP per day in the pool. So that means 183 BBP per day per machine. Meaning that your chances of hitting a 20K bbp block is one in 109 DAYS of mining.
So you could either let it solo mine and maybe you will get one in 109 days, or set it up for the pool. We have two pools: pool.biblepay.org and MinersOfMen.com.