Firstly, you need to have a pair of ankle boots/knee high boots. I used a pair of white ankle boots which I purchased from a charity shop. I then went out and bought some white faux fur pieces of material.
Get a tape measure and measure the circumference and the length of your boots (The circumference measurement will be the width of your fur material) Then add 1.5cm seam allowance to your circumference measurement.
Using your measurements, cut out two pieces of material (one for each shoe), then take your first piece and fold exactly in half, right sides together. Using a sewing machine sew a straight line down the length of your material. If you don't have a sewing machine you can easily hand sew it. Alternatively, you could use fabric glue but the finish will not be as good as a needle and thread.
Once you have sewn down the length of one of your pieces of fur material, turn it out so wrong sides are together and pull over your boot. You can then use glue to stick your fabric directly to your boot or hand stitch it for a permanent finish. If you want to allow your fur to be removable you can just leave it as it is!