I've made a tutorial showing my method of doing bindings. It may be a bit different than the way you're used to doing it, or you may be new to quilting & just need some basic how-to's.
I start off trimming backing & batting even with the quilt top.
Then, add up the length of all 4 sides, and figure out how many strips you will need. I always cut them WOF, or width of fabric (going from one selvedge edge to the other). Most of them have at least a 40" useable width. For this baby quilt I needed 5 strips. I am cutting the strips 2.5" wide.
Join the strips with a bias seam. Take 2 strips, and ay them out as shown here, right sides together. Sew on the diagonal.
Press the seam open to reduce bulk. You can use an iron, or I just run my fingernail along the seam.
Continue adding more in the same way, until you get them all together. Now, using your iron, press the binding with wrong sides together, matching up the raw edges.
Now you will be attaching the binding to the back side of the quilt. Start in the middle of one side of the quilt, and match up the raw edges of the binding to the raw edge of the quilt. Leave about 12" of binding free behind your needle. Later you will need this free part to join to the other end. I stitch about 1/4" away from the raw edge of the binding. I don't pin, I just hold a small section in place at a time, and stop to re-adjust often.
Now, when you get to the corner, stop with your needle down when you are 1/4" away from the end of the quilt. Pivot, and sew right to the very corner, as shown. Now you can remove the quilt from your machine.
Now, a little fancy folding will give you a nice mitered corner. First, fold your binding the opposite way of the next side you'll do, like so.
Now, place your fingernail right along the red line, and fold the binding back to the left, over onto itself.
Now take the quilt back to your sewing machine, and start sewing the next side down, starting right on the edge.
Now on to part 2......