Don't feel dumb, we all started out at the beginning at one time or another!! You are in a great place here with loads of knowledgable experienced knitters and lots of newbies too, no question is a dumb question!!
After you cast on, each loop on your needle represents one stitch. So if you have started off with a slip knot on your needle, that represents one stitch and you cast on 49 more to arrive at your 50 required stitches.