This really requires more than can be given in an e-mail, but here are a few things.

Once you have Drive open:

Jaws key-z to turn off the virtual cursor. It will turn back on every time you go to a different window, so you always need to remember to keep turning it off.

Once it is off.

gn puts you in navigation mode, and then you can use the arrow keys to find files and folders.

Gl puts you in files mode, so you can arrow up and down through the files in the current folder.

Enter on a file to open it.

This barely scratches the surface.  I recommend you find one of the many tutorials available for JAWS users online to learn the Google products.