The border is pinned in place but several inches are left unsewn at the beginning, thus your partial seam. This applies only to the first border. After it is sewn, you have a finished end.
Above see the other end of the first border, sewn all the way to the end of the white inner border.
Add your second border and sew from beginning to end, as above.
I did not measure these exactly to size since they were pieced, it was hard to get an accurate measure. I left a little on the ends and then squared it up each time a border was sewn.
This picture is of the fourth border and first, ready to be joined. You can see where I had the partial first border seam still open.
Now it is pinned in place to complete the seam of the first border.
And here it is - totally sewn.
Here is the completed top with a not so good picture of the borders. Zoom in and you can see better. I was just too anxious to get these pics up I guess.
And two empty containers, meaning I had used up all my strips and fabric from two shoe boxes.
And here is the pieced backing. I had several leftover blocks that were too small to fit on the front, therefore they became backart. I was trying to use all of Granny's strings and the yellow fabric, which was also in the container. I did add a few of my own to even it all out.
Now all that is left is quilting!!