get engine to TDC
undo crank bolt
pully off
plastic covers off
undo the 10mm bolt on the tensioner
hold tensioner to the side
take belt off..
at this point you can change the cam seal (recommended)
and the tensioner (if you buy a timing belt kit you get one with it, and a cam seal)
put the new belt on, making sure the marks at the top of the cam gear and cover are lined up, and the key on the top of the crank is at the top still..
do up the tensioner so the belt is tight.. not insanely tight.. just nice and firm..
covers on.
pully on..
away you go