This is what it looks like with the front to back seam sewn, now there is just the little seam at the crotch left to sew.
Fortunately I did a good job in matching the pattern. This is going to be the front. Sorry it's upside down, it's rotated in photobucket.
Now that the front is determined, it's time to add the cotton crotch. I've used tshirts, but now I have a bit of ribbing I bought in black, white and pink to chose from. It doesn't take much. I have put the RTW and my version over my ham. The RTW uses a diamond and tacks it down at the corners. I like a larger rectangle and sew it all around. Although it won't fray, I sew around the edges of the rectangle, I like the look and it keeps it from stretching out too much. This something I do differently than RTW, they centre it on the crotch, but honestly, that's puts it further back than I think is ideal. I put it 2/3rds to the front. I folded mine over so you can see where the crotch seam is.
|And the inside, all sewn down.|
Once that is sewn down, the last thing to add is a little bow to the front and you are done. Ta da!