Ah, it won't turn over, that's a clue. Should be straightforward. You will need to locate the starter motor. On this there will be heavy cables running to the battery, there should also be a small wire, it may be a connector. This is the solenoid connection, you should have 12 volts here when you turn the key to the start position. Perhaps your loose connector is the connector for this?
If you don't have a meter to check the 12 volts you can use a test lamp.
If you get no further let me know and i will check the wiring diagram, maybe I can help you with what connectors/ wire colours/ relays/ fuses etc. to check.
There should be a definite click when you turn the key, that is the solenoid engaging.