Visit the Tefal UK homepage - I Google sit and it was the first one in list. You will see the Q&A's drop down menu - select 'steam irons'. Answer number 4 will you the instructions.
Basically you fill the iron with water and switch the steam to dry. Then switch it on and leave for 5 minutes to heat up. Unplug it and hold horizontally over the sink. Remove the anti-scale plug (it just lifts out if you grip the sides) OR switch to self-clean if appropiate model. Steam and scale deposits will leave the iron through the steam holes. You can then vacuum the steam holes.
That is more or less word for word what it says and I have just this minute done mine. I have had it for 2 years and never done it before but not much 'stuff' came out. But I will see how it gets on!!
Hope this helps!!!
Kerry
November 2008