First, measure the thickness of the board into which you'll be drilling the pocket holes. (Note: You need to measure the side of the wood the screw will be coming out of.)
Next, you'll need to adjust the length of your drill bit to match the measurement you got from the thickness of the wood. Use the measurement tool in the Kreg Jig box to adjust the setting on your drill bit. (This is the little circle collar you'll be adjusting).
Set the length of where you want the pocket hole to be in the piece of wood. Again, the length should match the measurement you got from your board. These parts you're adjusting extend from the actual Kreg Jig.
Line up the kreg jig with the tabs at the end of the gray arms pulled against the end of the wood. Center the kreg jig on the wood. For a 2x4 there's room for both pilot holes; for a 2x2 center just one hole on the wood. Use the clamp to hold the Kreg Jig in place.
Now that you have the Kreg Jig set in place, it's time to drill. Drill until the collar that you adjusted in step 2 touches the pilot holes.
Next, attach your piece of wood using the pocket hole you've created. You'll need a driver bit at least 6" long, as you'll be drilling more depth.
Once you've connected the two pieces, you can now use a rubber mallet and a wood plug to hide the hole — a little sanding and staining and voila; it's like the hole was never there!