Step 1: Starting from the bottom, push the needle up a bit in front of the previous stitch.
Step 2: Pull the needle through
Step 3: Going backwards, push the needle back down where the previous stitch ended. Hope that isn't confusing.
Pull the needle through and you have a backstitch! The key is remembering to go backwards, because it is a backstitch. When doing curves, make your stitches smaller so that there aren't sharp edges.