If doing it the first time suggest setting aside a long day or better a easy weekend. The website www.autozone.com
should have details on changing the belt and water pump complete with drawings.
The job is not difficult, but doing it the first time requires figuring things out, getting tools, etc.
You will need to remove the crank pulley using a bolt on puller (not jaw type) to avoid damaging it. The bolt holes in the pulley are either 10 or 12 mm.
Prior to this you will need to restrain the pulley (crankshaft) to unbolt the crank bolt. Suggest fabricating a section of wood with holes that can be bolted to the pulley via the the bolt holes above. Fabricate a hole in the wood to allow allow access for the crank bolt socket.
Make the section of wood long is enough that when the crank rotates the wood binds up on the chassis or ground and prevents rotation.
Access to the upper engine mount bolted to the engine is limited but with a little patience the bolt can be unbolted (although not removed from the bracket).
Replacing the pump is straight forward. You only need to replace the pump, not take off the front engine housing.
Also at this time check for oil leakage at the cam, crank and oil pump seals. All can start to leak after a time. Check the idler pulley bearings for roughness.
There is no need to mark the belt as pointed out in many manuals, just line up the crank pulley at TDC and cam with the hole lined up on the upper cam bearing notch. Use a mirror if required to perfectly line up the hole/mark.
When rotating the crank CW tighten the tensioner bolt. Rotate crank 2 times CW and recheck timing marks. If off, make adjustments and recheck. It is possible due to belt slack take up for the cam pulley to rotate and be off. If so, do the job again and move the cam pulley forward or back 1 tooth.
The timing belt cover seal often is damaged or just old. If so use some silicone gasket material to hold the old gasket in place or repair.
After the job is done, re-time engine following the Toyota proceedure.
Suggest using a Toyota OEM timing belt (even if more expensive), have had issues of belt noise (whine) with other brands.