Boot manager error : how to make your usb bootable or how to install os from usb

U need to iso file to install your requires OS(try torrent for os)
Simply copying the iso file to USB shows Boot manager error
Try this method to install os from usb

Download: Rufus

Its an exe file no need to install just download and open

Click start
wait for the file to load in USB
Now Switch ON your PC
Tap F12 on keyboard
Boot window open
Select your USB drive and click enter
Continue with installation