Well you have two choices that I can think of off the top of my head.
The first is you can grow some stuff in planters. I actually went out and bought the big storage tubs that a lot of places sell. They are working pretty good. I bought different sizes depending on what I am growing in them. I put some lava rocks at the bottom and drilled some holes about 1/2 inch to one inch up. Put some soil, then some compost, and a final layer of soil.
The second is you can rent/buy a rototiller. Put some fertilizer or compost on top of the area and till it into the ground. Works well depending on your soil.
A third option I just thought of is taking a sample of the soil somewhere to be tested. They can then tell you what they would recommend adding to it, to help your plants grow. Do not forget though, different types of plants require different soil types.