First, you need to decide where to place your HD projector or multiple projectors. You can choose to attach it to a section of your ceiling or at higher level than the target surface itself.
Then decide where to place your LCD TV. There should be a broad enough distance between either your computer device or set top box and your TV.
Lay out all the cables and read how they're labeled. You should have both data and power leads. The box will come with DVI, composite, VGA, HDMI and component cables.
Untangle them and lay them out flat on the floor. Stretch them out all the way and examine the connectors. Go to the back of your TV and see exactly which TV jacks connect to each data and lead cable.
Next, align the target surface with the TV. Then go to the front or back of your target device to line up the jack connections with the free ends of the cables.
When everything's connected, plug the electrical supply cords into AC outlets. Turn the projector and the device on. Look to see that the view is clear and free of any visual interference such as furniture, shelving, glare from mirrors, and so on.
Realign the projector by moving the target surface or the projector itself to the correct position. If everything is connected okay, the projector and the TV will turn on and be functioning.
It's important to make sure the cables hanging down from the back of the projector from the ceiling are not obstructing the view from either direction. If they are, you should reposition the projector closer to the TV in a sideways direction. Just be sure not to mount it too close. That will reduce the picture's clarity.
Next, position your furniture around your TV so that you have comfortable positions to sit and relax on your sofa or recliner to enjoy your viewing. Test the projector to see that it's operating correctly.
If all the cables are connected into the appropriate jacks as described, then your projector will work fine. You can also check the mounting brackets holding the projector to the ceiling or wall. They need to be as secure as possible so the projector doesn't fall from any vibration occurring in the house.
That's all there is to the installation.