You can barely fit your hands behind the high definition TV mounted on your wall, but when you need to see what you're doing you can't have your hands in the way, making it nearly impossible to plug something into the back of your set. The High Definition Media Interface cable is ideal for home media setups since it carries both the audio and video signal, but if you can't plug the HDMI cable into your TV it won't help in the slightest. Depending on what you need to do you, can extend or repeat the HDMI port on your TV to access it while keeping the TV mounted on the wall.
Rotate or remove the TV from the wall bracket. Some wall brackets include a rotation feature to allow you to plug items into the back. If your bracket is stationary, you'll need to remove the TV first. Follow the instructions from the manufacturer of your wall bracket to remove the TV.
Attach an HDMI cable, extender or converter to the HDMI port on the back of the TV (see Resources). Use a cable if you are going to plug the TV into the same thing without changing. Use an extender or converter if you need to change HDMI sources. The extender is essentially an HDMI extension cord. The converter bends the HDMI plug 90 degrees so you can plug in a cable using less space behind the TV. When using the 90-degree converter, point the opening down so you can reach it with an HDMI cable once the TV is up on the wall.
Plug a cable into your source, for example into an AV receiver that can repeat an HDMI signal from other sources. Remount the TV to the wall bracket. If you have an HDMI extension, let the wire hang behind the TV where you can access it when you need to plug in an HDMI source.