Help! knitting! I don't how to do the ruffles in this pattern. how do you attach it to the main piece(back)?

The way to attach the ruffle to the main piece is to put your needle into each stitch until you have the required number accoding to the size you are knitting. The smallest size requires 35 stitches to be picked up. The next size 40 stitches, and the last size 45 stitches. That's on the wrong side. Turn the work over to the right side and knit 1, M1 means to pick up a stitch by going between the stitches on the row before, twisting it and placing it on the needle thereby creating a stitch. Continue the knit 1 and make one and you will see the work get curly.