Knitting my first socks - need help joining heel to instep

I’ve finished shaping the heel, now the pattern reads:

1st needle: With RS of work facing
and using the heel needle, pick up and
knit 11 (11-13) sts along side of heel.

Am I picking these stitches up from the rows on the side of the flap I’ve created in doing the heel? Do I go all the way back to the needle on which the instep stitches were being held?

That’s always hard the first time. This tutorial has great photos that might be easier to understand.

http://www.cometosilver.com/socks/SockClass_Gusset.htm

Thank you so much. That looks like exactly what I need!