No need to remove the fan at all.
Lock the crank pulley with a screwdriver so it doesnt turn when you undo the bolt, also put the car in 4th gear and pull the handbrake on so the motor cant really turn at all.
Remove the crank pulley (you may need a puller) and the big washer behind it.
Loosen the tensioner off and you should be able to slide the old belt off the tensioner (smooth surface), the belt should then fall off the top and bottom pulleys.
Make sure all the pulleys are lined up before you put the new belt on, pushing the tensioner in with a screwdriver at the same time.
As previously mentioned, turn it over twice before tightening up tensioner.
If the internal mark in the dizzy doesnt line up exactly, just loosen off the dizzy and twist it and lock again. No need to remove the belt again if just this pulley is wrong.
Ash