Those are so cute!! Nice job. I see two pictures but nothing with any brackets or red. What I'm thinking though from what you said might be something like this.
"Holding the soaker with the right side facing and the leg opening end pointing away from you, pick up a stitch in each purl in the line of purls you made earlier where I said the skirt would attach. To do this insert one end of the 16" circular needle only through the purl "bump" on the outside of the fabric (not through the whole fabric), yarn around drawing up a new stitch loop onto the needle. Continue all the way around. Join into the round and work as follows." Then tell them how to make the ruffle.
You may not have used that kind of needle or done things the way I said, but something like that. There are different ways to write patterns some are very cut and dried and some are more chatty, I think you need a few words here to make what you want them to do clear.