Select a curtain that will fit the room and the divider's function. For example, if you're looking for a curtain that will block some sound and light, it should be made from heavy material, like canvas. If you're looking for a curtain that is only a simple barrier to show a division of space, a lighter curtain may do.
Insert two 2-inch hooks on the walls of either side of the room, approximately 6 inches from the ceiling. Mentally name one hook A and one hook B. For an extra-secure hold, insert wall anchors into the wall before inserting the hooks into the anchors.
Cut a length of wire long enough to reach from one hook to the other with a couple of feet to spare. Fold the wire at one end and attach a wire-rope clip. Attach this end of the cable to hook A.
Stretch the other end of the cable to hook B. Clip the wire so that you have a foot of excess wire, and tie the wire to one side of the turnbuckle with a wire-rope clip so that the wire doesn't quite stretch all the way to hook B, but so the turnbuckle can expand enough to attach to the hook.
Adjust the turnbuckle so that it reaches hook B, but the wire is as tight as possible. There should be no dip in the wire.
Attach curtain hooks to your curtain wire, then attach the curtain to the hooks.