Hello. I am about to start a green house in Ohio. (I know I am crazy. There is literally snow on the ground but I want to get started asap and am willing to heat it and light it artificially.)

My question is this. A while back I had to dig a big hole in my back yard which left me with loads of dirt. There is a lot of clay in some of it and not a lot in some of the rest of it. What I need to know is what exactly I will need to do to make the soil ready for my vegetable garden. I know I will have to add sand to the soil with clay but I don't know how to test the PH ( just mix some dirt in water and test it? ) and I don't know how to test to see if there are plenty of nutrients. Also are there any other tests I should run? Any advice on how to do this would be really appreciated! Thanks!