Decks, Patios, Porches and Docks - Need help with a ground level deck

I'm building a deck over our concrete patio. The patio is 12'x12' and I want to build the deck 12'x20'. If I were just building over the existing patio this would be simple, however, because I'm going wider than the patio and this is a ground level deck it complicates things. I know I'm going to have to put posts in but how do I go about attaching a joist to them? Do I need to dig a trench that will allow for a joist and what size joist do I need? Even though this is a ground level deck I am still going to put a railing around it (to keep the dogs off). Also, if anyone knows where I can get deck plans for a ground level deck I would really appreciate it!
Thank you very much!

If your deck is right on the ground, you shouldn't need posts. The weight of the deck itself will hold it in place.
Just build a frame to install the joists in.
Use ground contact pressure-treated wood, and you can set part of it on the patio, and the rest of it on bricks or concrete cap blocks to level it. Lay them out where you would support posts.
I think that I would dig out any grass that is going to be under the deck, and spread ground fabric and gravel under it.
For general illustrated how-to info on decks, go to http://www.bhglive.com/homeimp/ and click on "Decks".
Good Luck!
Mike

I don't know why I didn't think of that! Sometimes I tend to complicate simple things! Thanks again!