Hi there! And welcome to sock knitting!
I remember the first time I knit a sock. It was SO EXCITING TO MAKE THE HEEL!!!
First of all....trust the pattern.
When it says to turn, just go ahead and do it.
Don't worry about the rest of the stitches on the needle. Just leave them there. You will come back to them soon.
When you made the 2.5 inch heel earlier, that was the back of your heel. If you look at a sock, you will see that part, going straight down the back of the sock.
Now, you are making the CURVE of the heel, so you will be making it more narrow, and the sides are curving in a bit.
You can do it!
You will see some nice photos and a great tutorial on turning the heel here: http://www.cometosilver.com/socks/SockClass_Heel2.htm
My friend Silver made that, and she is awesome.