When you made the two ear flaps you made them separately and bound off when you were through knitting them. They have had you use a knitted on cast on to cast on 25 stitches. Now hold one of the ear flaps right side up so that the wide edge is up where you can pick up stitches along its edge. Using the same needle that you cast the 25 stitches onto and using the same yarn that you were using for that, pick up 15 stitches along the edge of the ear flap. When you finish picking up 15 stitches from the first flap you will have the 25+the 15 stitches all on the same needle, and you are half way around the hat.
Look up what Jan told you to if you don't know how to pick up stitches. When it says to pick up and knit 15 stitches you are really just picking them up, but it sort of knits a row while you pick them up so it is called "pick up and knit". You will pick up 15 stitches along the edge of the flap and that is what attaches it to the hat. It will not seem very "attached" yet, but trust and go on.
Now that you have the 40 stitches on the needle and are half way around the hat, you next cast on another 25 stitches, then hold your final ear flap up with the wide part that you want to attach up where you can begin to pick up 15 stitches along its edge. After you have picked them up you now have all 80 stitches on the same needle, place a marker there to mark the beginning of all following rounds. The 80 stitches seem at this point to be just kind of sitting next to each other and don't seem very attached, but after you knit a few rounds, they will look more attached and you will see the hat beginning to take form.
I hope this helps you get a picture of what you need to do.