Very understandable. Take your time, follow the step-by-step. Keep track of where the wires are going so you don't get confused.
Technically speaking, all you gotta do to get the computer running and just into BIOS is:
-install CPU and heatsink (with thermal paste, etc)
-connect little 3-pin heatsink cable to CPU mobo header
-stick of RAM installed
-connect power cables to mobo
-ON/reset switch connected to F-Panel on mobo
-install graphics card (with power cable if necessary)
-connect monitor to mobo
-plug in PSU, monitor, keyboard, mouse
-turn on PSU, push computer ON button
That's it to get a computer turned on for the first time. You don't need a hard drive, optical drive, case fans, lights, etc connected to get into BIOS. This is a very streamlined installation if you want......just to see if it turns on.
I often do this with the mobo on a big piece of cardboard and all the parts (PSU, cables, etc) laying on the kitchen table. Easy to get to everything, lotsa work space, no cramped case, no extra wires. Make sure it turns on and get BIOS set up. Then off, and connect optical and hard drive. Then install OS. Then programs, etc. Then monitor temps, etc. Then turn off and install everything into case. Cable management and BOOM, done