How do you change an oxygen sensor on a 2000 Toyota Tacoma?

on you exg. there is 2 02 sensors. upstream and downstream up is before the cat, downstrem is after. most 02 sensors are a bolt desing and hold themselfs in, so under the truck find the bolt with a black wire looking thing after the cat bolted into the exg., disconect it from the plug an play point (sohuld be somewhere under the truck, not to hard to find) and unbolt it. then reverse steps to install.