I may fumble around this bit a bit, lol like I havent already with all the other parts.
FINISHING THE CROTCH
looking between the start and finish of the provisional cast on, you will see the end of your yarn (not the waste yarn) is looped through the first stitch, pull it out.
the stitches need to captured in 4 different lots, so recapture the stitches grouping them as such
place The 13 stitches between and including the yarn marked stitches(markers were placed in the first row) which are at the centre back of the body on a stitch holder, the 13 at the front on working needles. (both these lots will become gusset stitches)
place the remaining [33-43-53-63] stitches either side (these will become the leg stitches later) on seperate holders (placing them on waste yarn works best).
Working with the 13 stitches (front gusset stitches) on the working needles, join yarn and work 5 rows in stockingette stitch, begining and ending with purl rows
taking the 13 stithces from the back gusset, using kitchener stitch, join these together, end yarn.