It's not really as simple as it looks. There is a bolt to release the tension, but you'd need to take off your crank pully and lower you engine to get to it. and getting the belt back on is a PITA. If you slip up, you gotta make sure everything is back to the right timing.
I wouldn't attempt to do this without the manual. I just did my timing belt in about 15 hours

. But if you feel that you are capable of doing it and you have the right tools, go for it.