margecam52

I am assuming the grid is 1" squares.

I am going to assume the larger piece on the bottom of your drawing is 6-1/2" tall (looks a bit less, but you can always trim at the plain edge). That said:

The larger block should be cut 7-1/2" wide x 7" tall (this gives you a 1/4" seam allowance).

The top section:
Cut the middle fabric color 7-1/2" wide x 3" tall (again, this gives you the 1/4" seam allowance).

Your side pieces need to be 2-1/2" wide by 3" tall ( this includes the seam allowance.
Draw a diagonal line down the center (wrong side) of the side pieces..from the tall (3") corner down.
This line will be the stitching line. Note: I use a #2 pencil (the cheap mechinal pencils) to draw the lines..you want them really thin...if you have to mark on dark...use a light colored pencil..that is sharp.
You want to lay the end piece onto the end of the center fabric (right sides together)...matching the three edges...then stitch on the line (try to stay to the outside edge of the line). Once stitched, you want to open out the small fabric to make sure it will meet with the outside edge of the larger square exactly. Now is the time to make any adjustments needed to your stitching. Once you have made any needed adjustments (if any were needed), you want to press the seam (do not press open yet). Open out the pressed area & trim 1/4" from the sewn seam.
Now is the time to press the seam open, if that's what you want to do. I rarely press a seam open...that's a matter of preference though.

Hope this helps!