The steps for glue basting and pin basting a curve are essentially the same. First, you want to fold both you concave and convex pieces in half and finger press them so that you have a little crease along the center line. It is important to line your pieces up in the center so that you don't end up with too much bulk on one side or the other.
Next, rather than pin through these lines, put a small drop of glue on the center line of the convex piece.
Then, place the center line of the concave piece direction on top of this glue dot. You want to then set that glue using a hot dry iron.
Once you have your center set, you want to put a small dab of glue right on the left and right edges of the convex piece.
Then, just as you did with pinning, bring the edges of the concave piece up to meet right on top of those glue dots. Again, heat set your glue with a hot, dry iron.
Now, if you are comfortable with curves and your machine, you can stop here and align the rest of the edges as you sew. If you want your basting to give you a little less movement in your curve while you sew, you can add more dots between the ones that you have already heat set just as you did with pins. The number of glue dots you use is completely based on your comfort with your curve and how much control you want to have when sewing it.
So you have the instructions on how to trim the blocks in your pattern, but I wanted to go over it really quickly in case it doesn't make sense for everyone. Basically, you need to just make sure that you have only a quarter inch of background at the edges. That way, when you sew two hemispheres together, they touch.
So line up your ruler so that you have the quarter inch line laying on your seam ON BOTH EDGES. If you don't line both edges up, you will cut your background wonky.
Once you trim your background fabric, flip the block 180 and trim the other side. And there you go!
Sorry this got up late! I was having some super huge technical difficulties. :( Thanks for the patience!!