PhilDrudd

Yea as I said 
Re seat everything 
Make sure the front panel connectors are plugged correctly. 
Clear the cmos 
 
Again, do this ^

Can't really see because of the cable that's in the way
Boot the system up and if it didn't boot check for a light.
 
And do this ^

I don't recommend motherboard RAID. It's not good. Not to mention RAID is not a backup. If you plan to store important project files and documents on this machine you should look into a NAS and/or cloud storage.
 
If you want to play with RAID for your local bulk storage look into Windows Storage Spaces. Keep most of your important project data on that (it'd be your D:\ or E:\ drive) then backup over the network.

RAID is just an option. If you don't think you need RAID, you don't need RAID. lol. 
 
Don't worry about it :). If there is an option in your BIOS SATA controller options for RAID, IDE, or AHCI, pick AHCI.

You need 2 identical ones or you'll be wasting the bigger one's capacity (RAID1 with 1TB and 4TB gives you 1TB), and it would only protect against a small subset of potential failures. Better do completely independent regular backups on an external drive.

It's a feature that's available if you want it, no need to care about it at all if you don't.

You don't need to have your drives in a RAID if you don't want to.

Here is a good one on best-buy: https://pcpartpicker.com/product/J7F48d/cooler-master-mwe-gold-650-w-80-gold-certified-fully-modular-atx-power-supply-mpy-6501-afaag-us
 
Edit: Just noticed it's sold-out sorry... But the one you postet is fine. Basically can't go wrong with Seasonic as long as you stay away from the cheapes of their models.

The Focus GX is a good choice, so you're golden.