How do you restore backup files that was stored on an external hard drive back on a restored computer?

My computer crashed last night and was not able to restart at all. So, I had to backup all of my files onto an external hard drive and then restored my computer to original factory condition. I am having trouble restoring my backup files back on my computer, can I get help with this?

unless it came with some sorta back up program you will have to return everything manually