making my emulators run

I know that this question has been asked before......but the answer went totally over my head (being new to this and all).

I have managed to get to the stage where I can use flash fxp to gain access to my X box (preChipped, dashboard installed etc).

I it shows many things installed that i can't gain access to via direct access from the xbox (everything was pre loaded when I bought the x box)

I noticed that it has already got emulators.

The big questions;
is how do access them direct from the xbox?
more importantly do i need them to play games that have say for example the Sega logo on them?