Do you know the three types of video connections? They are composite, s-video and component. Compisite is a single video cable that has yellow at the end. This should be what you have on the Xbox. The compisite can go into the 1050. s-video is the next step up. It is a single cable that separates the signal so that it is transfered more purely. This can also go into the 1050. Component is the best available video connection. It looks like compisite, except that there are three of them. This connection splits the video into three colors. This is the type of cable that has to go directly to the TV as the 1050 does not have component inputs.
So, for your current setup, you'll plug the yellow composite connection into one of the video inputs, and the two audio connections into the corresponding audio input (the set directly below the video you chose).
Component and composite are easy to mix up if you haven't seen them before. We've all done it at some point, so don't feel bad.