Downgrade to win 8; no os

Had Win 8 and upgraded to Win 10. Did not like and reversed out, Win 8 was gibberish after the reversal. So I decided to use Wipe Drive to clean HHD and a fresh Microsoft disk to load Win7.
I get this error message "OS not found" any way I.try to load the software
I have used Wipe Drive before and never had a problem downloading an OS. All the F keys.produce the same error message. Would appreciate a little hand holding to load an OS.
 
Great response and most helpful, I was not aware of secure boot.
I have tried to get to the BIOS, but have been unsuccessful.. Pressed all the F keys and esc on startup with no luck. Still get error message OS NOT FOUND. I even installed a HHD with windows 8 or ten and still got the same error message I know I have to get to the BIOS, just don;t know how.
 
BIOS access key is often F11, or F12 or Del.
Just for info. After entering the BIOS, boot, had to change to Legacy to get Win 7 to load. On the Efxx (can't remember correct name) it would not load. Also the network controller driver would not load. Got on internet with WiFi dongle.
 
Not coerce, it sounds so corrupt, I prefer to finesse it. If it doesn't work the first time, use a bigger finesse hammer.
 
Signed vs unsigned drivers is a setting choice the user can make easily.
 
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