A hanging sleeve is used to hang a quilt on a wall. It is basically the same thing as a rod pocket on curtains.
To add a sleeve to a quilt, first make a 3" - 5" tube of fabric. For an older quilt, I recommend using muslin.
Then, hand sew it to the top edge through all the layers of the quilt. Last, flatten out the tube and sew its bottom edge to the quilt.
If you are making a quilt, you can use fabric to match or coordinate with the back. You can also include the top edge of the hanging sleeve right into the sewing of the binding on the top edge of the quilt. Then just hand sew the bottom edge of it down.
In the picture, I've used a wooden dowel rod and heavy duty thread to hang the small wallhanging from a nail in the wall. Wooden rods can cause older fabrics to deteriorate. So for older quilts, a non-wood rod would be the best choice.
Sometimes on wall hangings, I will make a few little tabs to run the rod through instead. They are exactly like the tabs on tab-top curtains. I space them evenly across the top edge and sew them on when I do the binding. To space them out, I put one on each outside edge and then every 4" - 5" in between.
Just make sure that the stitching is securely fastened. You don't want it to come unraveled and have your quilt fall to the floor!