Do what rocky suggested, download the media creation tool and use it to make a USB and then clean install as updating from 10240 to 15063 has proven troublesome in past and clean install is fastest in long term
backup anything on C you want to save
change boot order in BIOS so USB is first, hdd second
boot from installer
follow this guide:
http://www.tenforums.com/tutorials/1950-windows-10-clean-install.html
when you reach the screen asking for licence, click "I don't have a key" and win 10 will continue to install and reactivate once finished
On the screen where you choose where to install win 10, if it gives you an error about GPT drives, delete all the partitions on the hdd and press next. If it still gives error, cancel out of the installer and restart PC and start installer again, it will accept next on that screen this time (some PC just need a restart here)
10 series cards do have problems installing drivers on old versions of win 10, hence his need to update to at least the anniversary edition. Since you can't easily get that version now, CU is best chose.