Don't give up, get in a class and get some help. You did a great job all by yourself so you know with a few classes you are on your way to many new and exciting days of quilting.
The hanging sleeve can be made several ways, as others have mentioned or I cut a muslin or matching backing fabric the width of the quilt at 4 1/2"wide. Fold the two short ends by folding in 1/4" twice and sew along the edge so there are no raw edges on the ends. Now fold lengthwise right sides together and sew 1/4" seam. Turn and hand sew along both the top and bottom just bellow the binding of the wall hanging making sure you center it. You can use a dowel rod or a yardstick to hang. Any questions feel free to ask, we all love to help each other. Bernadette