Your main battery negative cable goes down to the front side of the block, right next to the starter.
Another ground is located on the back side of the engine just behind the oil pressure sensor. Its a smaller one, but its needed.
If all seems good to go, take a screwdriver and jump the big and small terminals of the starter. If it arcs and turns the engine over, then your issue is elsewhere.
Turn the key to on, then repeat the above procedure. If the car starts and runs, then we need to look elsewhere.