help electrical problem, Fuse box short engine compartment, and passanger.

[95blk5.0stang]

I was in the process of finishing my rebuild. I forget to ground one of the cable up under the engine block and believe to short out some parts of the engine compartment fuse box. My test light lites up on some connections but not all. In the passanger compartment some light up but not all as well. What can i do about this is there a wiring harness for that runs to both. I need help will it be hard to do myself. it might cost to much to send to a shop. I might be making it bigger than what it is. So when I tried to crank it a few times I show the negative battery terminal smoke and I check to see why in saw I over looked the ground to the block. When I turn the key all power is lose and the volt never reads above 10v. Help please.