There are two types of fusible webbing.
One type has fusible on only one side. Suppose you have an orphan block - - say, a 9 patch ... stitch the fusible, right side of the fabric to the glue side of the webbing (do not use an iron yet) ... stitch around all four sides of your block. Carefully lift the webbing away from the block and cut a slit in the webbing - - you will turn the block to the outside, which will put the glue side of the webbing ready to be ironed into place on your quilt.
It would be a good thing to purchase a teflon sheet designed to withstand being ironed for the next step.
Following the ironing instruction on your webbing sheet, glue your block to your quilt. When it has cooled, you can use any decorative stitch to top stitch the edges of your block on to the quilt top. Easy applique ...
if you don't happen to have a block, then cut around a picture in your novelty fabric, follow the same instructions, and VIOLA! You have created a theme quilt. I am going to look for a link that will help you see how to use the single sided webbing in the manner to which I am referring <wave>