The 1ZZ-FE ('98 - '08 non XRS) has a belt tensioner you slap a 1/2" ratchet on and turn away from the belt to slide it off. Belt tensioning is done automatically.
The 2ZR-FE ('09+) has two bolts that attach the alternator, and a third bolt sideways to the alternator. You crack the two main alternator bolts loose, then loosen the third bolt to remove the belt. Once the new one is on, you tighten until the longest run (which is crankshaft pulley to alternator) has 1/4" deflection. If you go too tight, you'll trash bearings. If you go too loose, belt will slip. Then you tighten the alterator back up. It's not as simple but there really isn't room for a tensioner on these engines, so they went old school.