how would i get to the drain hose from the A/C cooling coil?

I mentioned in an earlier guestionaire, that i believed my heater core to be leaking antifreeze, and was told it could just be a clogged drain hose from the A/C cooling coil.

Now i needs to know, how to go about locating the drain hose, removing it; then reinstalling it.

help me too gain insight of this please!