Find your alternator and follow the power lead to the fusable link or follow the red wire coming off the battery these two wires meet at the fusable link. Usually located under a slideout or bolted-in section on the side of the main engine fuse panel.
If you have power(from known good battery) to starter and car wont turn over you have a bad starter.You have to check the thin wire with a prob while somebody turning the ignition switch. It has to be power in wire while key in starting position. If no power there it could be: -starter relay -ignition switch -fuse.