exporting tracks

I am trying to export multiple tracks into one mp3 file. Every time I try to export multiple stereo tracks (2 or more) it says it will be mixed down to only two stereo channels. Now it is just one long file and does not show individual tracks
I want to be able to make one mp3 file and when it is played I can press the fast forward arrow and it will move to the next track in the mp3 file.
I cannot figure out how to MARK the tracks.

Plain MP3 doesn’t support chapter markers, but there are extensions that may do what you want. Scroll down to Chapter Markers.