mercruiser how to make the propeller spin?

[harnarl]

I just bought my first boat and its very old like 1973. It starts runs and "seems" to run really well. however i can't figure out how to make the propeller spin... it might be broke i just don't know anyone have a suggestion?
It has an inboard motor i tried lowering it closer to the ground and i have some water muffs on it, while its started i push the lever forward and it seems to go in gear "seems" when i go to the back of the boat the propeller isn't free spinning or anything...

[Frosty]

You cable needs adjustment ,Is broken or the gearbox has failed internally.

Keep away from that prop,-- Keep children away it will kill.