well, if you want to go all the way through your paint down to bare wood, use the 60, a 100 is what I've been using to get through my pain all the way, and it's taking longer than I'd hoped. the 240 is pretty fine grain, that's the kind of stuff you'd use for a final touch-up before re-painting.
you could also run down to home depot or lowe's or whatever home improvement store you have there, and pick up a sponge sander for less than $5. they're pretty nice in that they can form around edges and stuff too.
if you just want to do sanding on a flat surface, get something like a small piece of wood, like a 2" x 2" square or something, and attach the sandpaper to one side of it, then you can grip it and sand away. it's easier than trying to just use sandpaper.
