That's a pretty open question there!
For example what is your intended look?
Mirror doors?
Panel doors?
Sliding doors that fold back into a pocket each side?
Do you intend fitting from floor to ceiling or stopping short?
Are you building a box to fit or fiting into a recess?
The sliding track is really going to depend upon how you want things to work, the more you pay the better the track usually. It's nice to have a soft close action on sliding doors otherwise they just bang when closed shut. Ironmongery direct might be a useful place to start.
Some pictures of the intended location along with some sketches would be a good start, also a few ideas of the look are going for.