In very general terms: you need unencumbered wall space a little over the nominal width of the door. For a 30″ door, you need about 63″. Any wiring or plumbing in that space will have to be moved.
Cut open the drywall, remove studs that are in the way, install a header over the opening, install jack studs to support the header, assemble the track to the frame, install the assembly and fasten it to the floor and the header and the jack stud on the open side, trial fit the door, remove the door, drywall, install the door, trim, paint.
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