When you hook the battery up connect the positive+ first, than the negative- for safety reasons, (disconnect in reverse). I would follow the ground wire to the engine by the starter and be sure it has a good clean connection. Be sure the battery has a full charge or it won't start. If in doubt, bring it to Auto Zone and they will load test it for free. Just because it has 12 volts doesn't mean its good.It could have a bad cell or 2 and not have enough amps to turn over the engine.
Keep us posted on you progress.
Karl