follow the instructions on the xbox manual. they are clear, I did one a few weeks ago.
for the xbox it is only electric plug and HDMI plug. leave the rest/
if you have HDMI cables (they are large rectangluar plug like things, well larger than a USB) then you put one in the tv end and the other behind the device. Or you will have AV cables (red, white and yellow) they will be 'out' on the device and 'in' on the tv
Didnt think either need 'installing' more like just plugging in? Maybe things have progressed over the past few months .......
Are the instructions no help at all?