Troubleshooting Help:

http://pcpartpicker.com/list/cqRWZ8

So I downloaded the Windows 10 iso file, and since I have a MacBook Pro with El Capitan, I couldn't use boot camp assistant to create a bootable USB(isn't an option in Mac OS X El Capitan), and so I searched around online and found a method to create a bootable USB drive using terminal(It did seem a little sketchy though). When I did that it seemed like it worked, but when I actually plugged it into my new computer, the only message I got was something along the lines of:"PLEASE INSERT PROPER BOOT DRIVE AND REBOOT AGAIN" I would get that same message whether or not the flash drive was plugged in. I know that my computer recognizes that the USB is there because in the BIOS settings it listed the flash drive as being there, and also I've plugged a mouse and keyboard into all of the USB slots on my computer and they have all worked.

But that's not my problem

So what I did next was that I had the idea to use my sisters MacBook Pro to create a boot drive since she had not upgraded to Mac OS X El Capitan yet and thus I could use an official program to make a bootable USB drive, and so I made a bootable USB using boot camp assistant(this time also using a different flash drive too.) but this time when I plugged in the flash drive the only thing that would happen is that I would get a screen that has a flashing cursor/underscore on it that never goes away. Can anyone help me with this?

Extra information: When I built my computer, I pretty much just followed the Youtube guides on picking parts/building the computer/installing OS software put out by newegg. Also I've tried messing around with the BIOS boot priorities in both my first and second try but nothing worked.

Tl;dr Used boot camp on a Mac to create a bootable USB drive with Windows 10 on it, plugged it into my build and it didn't work.