Having a bit of trouble understanding how to correctly make the star stitch

Purl 3 stitches tog and leave them on left needle,wrap yarn around and purl the same 3 stitches again .

When I do this it add stitches ,thanks in advance for any help

loomingranny/aka Terri

You should be adding stitches to make up for the 2 decreased in the p3tog.

Thanks Sue ,I wasnt sure about making a stitch when i was doing the star stitch ,but you explanation makes sense.
Thanks for your help , Terri