Does anyone know if their is a online step by step process on how to change water pump on this type of car? Or could someone tell me how to do it? Am not mech dumb just like to know what i'm getting into befor I start

I have a 2001 Toyota sienna that is coming up w/several misfiring codes. The first time we had it read it had misfiring codes of p300, 301, & 302. We changed the spark plugs. It still wasn't working right so we changed one coil, and had it read again. Now it comes up w/ 300, 301, 302, and 306. The check engine light goes between on and blinking on and off. Do you think this is just a coil problem and I need to replace more coils. Am I reading the manual wrong for which ones to change. We changed the front one to the left if looking at the engine from the front of the vehicle. I though I read that to be 2.