Make doubled line/loop at end of leader or mono running line.
Next "fold" the doubled line into a loop.(pic 1)
You then pass it through the eye of the loop in your "rig" whether it be the dropper of a snafu or the end loop of a pre-snelled hook.(pic 2)
You'll then pull the hook(s) through the loop of the doubed-line. With a snafu you have to make sure both hooks go in/out the same way.(pic 3)
Tighten it up a bit, adjust height if necessary, and then take the sinker and tie an overhand knot "around" the rig. (pic 4)