Hi blacklabbob,
There's a bracket mounted to the wall and a mating bracket mounted to the TV. The TV bracket hangs on a rail that's part of the wall bracket. The rail is located in the upper half. The bottom half of the TV bracket is "locked" against the wall bracket by a setscrew. Sometimes you can pivot the TV from the bottom by applying a little pressure to flex the bracket past the setscrew. Worst case, you might have to loosen the setscrew. The attached picture is probably not quite what you have, but should illustrate the concept.
The issue where it works on antenna but not on cable is most likely not the connections, since the same coax supports both functions. When on antenna, the signal booster needs to be ON. For cable it has to be OFF. The signal booster is often located in the bedroom, sometimes near the TV, sometimes in the closet. There's a little red push button and a red light that indicates that it's ON.
It also could be that you need to go to the TV menu and change from AIR to CABLE and do a channel search.
The color issue could be how cables are connected, but also could be the menu setup on the Toshiba. I think Toshiba has a ColorStream mode that's used with component video connections. You probably have AVI connections (Red/White/Yellow). If set to ColorStream mode when using AVI connections, you may get black and white.
Let us know what you find.