There are loads of threads on this if you search for it, but basically it's not the easiest ever. At least you don't have the balancer shafts belt and tensioner to do as well tho (1.8 and 2.0 only)
You need cam locks as well, to lock the cams in place while you change the belts. You can't just line up the pulley marks and go as it has a timing variator on the end of the inlet camshaft. The variator may want looking at too. If it makes any kind of "rattling" or "diesel" noise at start up you may as well change it. If not then leave it till the next change!
Plenty of guys on here have done their own but it's not much more expensive to take it to a specialist (assuming you know one who charges reasonable labour rates!).
Cambelt kit is around £70 for the 1.6 but NOT from the dealers! Try Alfa Workshop or EB Spares....for the cam locks as well.
Also you might want to check the water pump as well - about 40 quid and the impeller CAN warp on the TS ones. You can only change it with the belt off.