So you want to put a wood deck on a cement patio? That is not such a big project. Is your cement patio in good shape? That is the important consideration. If the present patio is sound and level a lot of the work is already done for you.
At your local home improvement store you can buy pre-made concrete bell-bottom anchors that have brackets attached to them for 2” X 4” floor joists. All you have to do is set them down, line them up, and nail away.
When You Need to Extend