Directly behind the timing chain cover which is attached to the engine, on the passenger side of the engine. It is completely sealed so you cannot see it at all unless you remove the cover. It should not need replacement unless you are having a problem that can be attributed to the timing (there is no preventive maintenance replacement interval).
It comes with a chain.
No. Timing belt. Not chain.
4 cylinder Toyota Tacoma's have a timing chain. The V6 has a belt.
chain
The 1.8 liter 4 cylinder engine in a 2000 Toyota Celica has a timing CHAIN
timing belt
It has a timing belt.
belt
1998 and up 4 cylinders have timing chains not belts, which means it is not necessary to replace.
It has a timing chain that should last the life of the engine.
The 2.2 liter four cylinder engine in a 2000 Toyota Camry has a timing BELT
Your 2000 Toyota Celica has a chain and not a belt. The chain requires no maintenance.