If I have an outline of an object (lets say a circle., and draw my own text, is it possible to fill ONLY the inside of the original object with the other object? I will be drawing my own "text". And NOT have the outline of the original object. The outline only being where the text would meet the circles edge.
I have searched and can't locate what I'm looking for.

I'm not entirely clear what your trying to do, but I think clip is what your after. If you clip an object with another object only the area enclosed by the clip shape is visible. (so in your example inside the circle.)

I have another idea what you might be after: flowing text into frames. Create your circle object, the text object, select them both and choose Text > Flow into frame (Alt + W.)

Ditto prkos, and then either remove stroke of circle, make it transparent, or zero width. And clipping works as well, per Simarilius.