i put maybe a dime (or 1p for the english peeps) sized blob onto my palm and then use a finger on my other hand to apply it to clean, just washed and dried skin, before bed- using little dabs and smoothing them (don't rub, you'll just clump it all up, you want it to slide into your pores) - onto my forehead, sides of nose, chin, and inner cheek area- dabbing onto and smoothing into one section at a time (cos it'll soak in pretty quickly- don't put a blob on your chin, then do your cheeks, and come back to your chin to rub that blob in, cos it might be gone already
then i wash my hands so i don't treat my finger and palm as well, cos i aint got any blackheads on my hands.
you leave it on (well, soaked in really) overnight like you would a moisturising lotion, and just wash your face like normal the next morning. your skin will feel smoother (especially if you get annoying flakey bits if you have zits or dry skin) and your blackheads will be much less... blackheady.
remember that less is more- you can always start off with a teeny amount and add a little more than before, a few days later- once you've seen the effect of a little bit, but if you go mental with it and use a golfball sized amount you'll not love it- you'll wake up with skin thats a bit toooo smooth and maybe a bit pink as well, cos its an exfoliant, and you know, its generally felt that its good to have plenty of skin on your face...