Before your TV can capture any channels, you need to first set the TV to "Broadcast", "Antenna" or "Air" mode (NOT CABLE), then perform the “autoscan” function to look for channels. Every TV has different working and menus, so you may have to look at your TV's manual to find the exact process.
Without performing the autoscan, your antenna will not work.
After installation or movement of your TV antenna, you need to perform a TV Channel Scan again. Every TV is different in how this is done, but we have amassed a list of channel scan links for all the major TV brands:
http://tv.manualsonline.com/ - This site can be very helpful if your TV is not listed below or if you do not have your TV's manual laying around.