The best way would be to use a green or blue screen as your background. A painted wall or a colored cloth with 100% green or blue.
Then on the time line put the background you want under the clip of you in the chair. Just make sure your background doesn't have the colors you chose. In MEP go to effects and select chroma-key. Not sure that's what it's called exactly.
You can buy the colored backgrounds from camera and video stores. Depending on size, can get fairly expensive.
This is Chromakey a green clotch as background well lith using fluorescent, the talent (you) about 2 meters from the background. The talent is lith using 2 softboxes place at 45 degres each side and 1 light in the back to lith by rear on shoulder level with one light just to separe the talent from background.
Using Video effect Chroma effet you can remove the background movie.
Normaly track 1 contain a picture with the new background or a movie
Track 2 contain the talent with removed background.
To test your setup just bought a strech cloth color pantone DS 284-3C or something near CMYK 60-0-70-20 or mat paint like this color.