All quilts need a hanging sleeve or hanging tabs so they can be hung either after washing, for a quilt show, or to be displayed on a wall. There are a number of ways that this can be done however if your quilt is intended to be hung in a quilt show, always check their requirements as each show may differ in the type, size, and construction they want.
Sleeves and Tabs are usually added to your quilt before finishing off any binding, however there are some exceptions. If you have not added your binding before you do this, ensure you square up your quilt first. You can find instructions for this here: How to square up a your Quilt
My preference is hanging tabs however most quilt shows will stipulate a sleeve and because each set of instructions is way too much for this single page, I'm going to provide links to the various techniques.
Hanging Tabs: My favorite because it is quick and simple.
How to Create Hanging Tabs
Hanging Sleeves: I am including two sets of instructions for making a quilt sleeve.
How to Make a Sleeve by Hand and How to Make a Sleeve by Machine