I don't about you guys, but underneath my hood, there is a sticker there with illustration on how to replace the coolant.
(*Make sure you are parked on a flat, level ground*)
Simplest way taught to me by my local mechanic shop:
To replace coolant, jack up the car, put on jackstands, take off the radiator cap, locate the coolant drain bolt on the lower part of the radiator, untighten the coolant drain bolt but don't loosen it, lower the car, now remove the plug and let the coolant drain out. (*make sure you something to catch the old coolant*)
-This next step is OPTIONAL, use a waterhose, run the water, place the hose the radiator cap opening, have a friend turn on the engine, and let it flush until you see the coolant existing the drain plug hole turns into water. This step is optional but it helps take out all the old coolant and any dirt or crap in there.
*Almost all mechanic shops do not do this step because if would be time consuming and a mess in the shop, they just drain the coolant and refill it*
-Once it's clear, put back the drain plug, and tighten it. Then refill with 50/50 mix coolant/water. Best is to buy the Toyota coolant if you can, it's premix 50/50 or the aftermarket brand like Prestone.
HTH