I found an old master lock pad lock in my house and my dad offered me a 100 bucks if I open it. I have no idea where the key is and I really need he money. Any body got some tips?

If you can bring the lock into a 'keymaster' usually where keys are cut they can make a key for the lock.

There may be a serial number on the lock where they have a starting point,or start from stratch and cut a key according to the barrel on the lock.