LOL, no you don't! It is a single crochet stitch
1) put two pieces of a garment together, right sides facing each other.
2) align the edge stitches
3 grab your work yarn that you used to cast off and make one starting loop (like beginning of a chain stitch)
3) insert the hook trough both edge stitches on one side, grab the yarn on the other side. now you have two stitches on the hook. grab the yarn that is still on the other side and pull through both loops. rinse, repeat
now, before I make pictures or a video...
just in case, if it's not clear what 'the other side' is. imagine front and back of a sweater, for example, facing each other and making 'a wall'. if you hold it vertically, you are on one side of the wall, you go through the wall with your hook to grab the yarn that hangs on the other side. then you go over the top of the wall to grab the yarn and pull through both loops to form a seam 'on top' of the wall.