What you need:

I'm using my BERNINA #1 foot and my BERNINA #5 foot (it's my stitch in the ditch foot).

Steps:

I press one side of my seam binding open.
I like to start in the middle. Notice that I folded the end down at a 45° angle.
Sew until ¼" from the end.
It should look like this when you're done.
Fold the bias tape back over the stitched angle.
The fold it back over from the edge. It should look just like this. From the corner, sew all the way down to ¼" from edge and repeat previous steps. Do this all the way around.
When you get to the end, cut this side of the seam binding the same length as the 45° on the other end.
Now, let's turn it over...
Turn the end under so no raw ends will show from the back side.
Fold the corners down.
Secure with pins.
I use my stitch in the ditch foot here.
Press and it's all done!