|Because several have asked about this before...the best online instructions and drawings for how to make the ball knot and simple frog design is located at:
The key to making them is to be ready to play. You can use either purchased cording that matches or make the bias tubes out of the desired fabric. I would not attempt the latter without the Fasturn tools to help you turn the tubes so much easier. If you don't have this, Nancy's Notions or Clotilde carry online.
I start by cutting out 1.25" wide bias strips of fabric. For a fairly simple frog closure like the one noted above, you will only need 2 strips about 18" long each. Align the long raw edges right sides together (but do not press the folded edge) and stitch about 1/4" from the folded edge, using a 2.0 or 1.5 straight stitch. Stitch across one end of the tube...and do this a couple of times to reinforce. Cut off the excess fabric so that only about 1/8" is left in your seam allowance.
Use the Fasturn tool to turn right side out, but just as you start turning, stick the tip of the cording (rattail works great for this as does cotton cording from the upholstery dept) into the end of your Fasturn hole. As you start turning it, it will now pull the cording into the tube as well.
As to the design part, I play with various options or clip out photos. Once I get a design I like, I use pins and fusible strips of Steam-a-Seam Lite 2 on the backside to hold the design in place until I can hand sew it in place. The important thing to do is to play with placement so that ball knot and the loop that goes over it are aligned well. For a jacket that meets in the middle, it has worked best for me to place the ball knot so that it is about halfway hanging off the edge of the jacket. Then, the loop is placed a little more than halfway off the edge.
Make sure the ball fits through the loop somewhat snugly but not tight. If you end up with over large loop, you can pinch part of the loop together and stitch across it to make a smaller hole.
The unfinished ends can be tucked under your design....or tuck the raw edges up into itself and then use a bit of Stitch Witchery to fuse it shut. Strips of Steam-a-Seam Lite can be used on the back of the frog design to provide some tackiness to help you place the design where you want it. Just make sure the fusible does not show from the front. Once you like your frog placement, you can steam press from behind the frog (not much pressure but use lots of steam) to fuse and it will help hold everything in place until you can hand sew.