Step 35 - Take one Front leg piece and pin it to its coordinating Back leg piece at inseam, with right sides touching.
Stitch. Finish seam allowances in your desired manner.
Press open or toward one side. Repeat for other leg/side.
I like to press the seam allowances of one leg forward and one leg back to reduce bulk at the crotch seam.
Step 36 - Place one side on top of the other, right sides touching, matching up the crotch edges. Pin.
Step 37 - Draw a line, with a temporary marking tool, from the dot up to the notch along the center front seam.
Step 38 - Starting at the top center front notch, baste down to the dot. Backstitch at dot, return to normal stitch length, and continue stitching around to the back at a normal 1/2” seam allowance. We will open the basting at a later step for the faux fly.
Without trimming, finish seam allowances together by either serging or zigzag stitching.
Step 39 - Press and pin seam allowances and fly extension toward left side when wearing.
Step 40 - With the right side facing up, and the back falling down and out of the way, line up your Topstitching Guide with the top of your Front and center front seam line. Use a temporary marking tool to mark the outside edge of your topstitching guide. 
Step 41 - Starting at the top, topstitch along your marking, backstitching at the end. Run a second line of topstitching 1/4” inside the first, backstitching at the end.
Step 42 - Starting 1/2” up from the bottom of your fly topstitching and in the left side (when wearing) of the garment, topstitch 1/16” inside the entire crotch seam, catching the seam allowances underneath. Run a second line of topstitching 1/4” inside the first.
Step 43 - Sew a small bar tack at the top of the two rows of crotch topstitching and a second about 1” up along the curved edge of the faux fly topstitching as shown below. You may want to practice your bar tack first. My preferred settings for a bar tack are a ziz zag stitch with 0.5mm length and 2.0mm width.
And that is it for today.