How 2 download from laptop 2 ext. hard drive?

Hello,
I'm a computer illiterate. My friend set up a seagate external hard drive for me. He transferred all my files and told me to continue transferring on a weekly basis. I can't find his instructions or reach him. I put the usb cable from the hard-drive into my laptop; went to "my computer" and activated the hard-drive. I wanted to have all my files automatically transferred so I didn't have to go through every file and figure out which doc was new and which doc had already been saved to the hard drive. Couldn't figure that out. So I tried the slow manual way of going into each file I thought might contain a new doc. Noticed that only once did I see files flying across the screen (indicating they were being copied). The other times I tried to copy files to the hard drive, there were no files flying across the screen. I know that the files I clicked on included new docs that had never been copied to the hard drive and wonder why on one occasion files seemed to transfer and all the other times, there was no movement of files? I don't have time to work this problem "manually" and hope someone can give me a clear step by step process of what I need to do. Thanks in advance!