You can go to the very left of the guide and as you scroll down to each channel you can choose each channel you like as a favorite channel. Then when you go to the Contour home page you click the option "Favorites" and the TV guide will only show all your selected favorite channels and all of the channels you don't like won't show up in your favorites tv guide.
The problem is that only works within the guide. When you drop out of the guide and are using Channel Up and Channel Down it completely ignores your "Favorites" settings in the guide. Looks like a design flaw to me. Sure hope a future update will give us the ability to apply the "Favorites" guide setting to the Channel Up/Down function.
Select: Settings > Channels > Set Skipped Channels
Follow onscreen instructions to skip channels you don't want to appear in the guide or to be selected when pressing Up or Down channel selection. It requires a bit of effort up-front, but you should only have to do it once.