How to put data onto an external hard drive?

My dad got me a 1 tera-byte sea gate external hard drive. He says I can put info on it like photos and files, and that I can backup some of my indo. I wanna save some stuff such as my minecraft files and downloads on it. So how do I put my files on it?(I have no knowledge on this stuff)And how do I put the info back into the computer, Because my dad is gonna reset the computer and then I'm gonna put my files back in.

p.s I got windows 7

Alright; here is what you're going to want to do. Use the USB cable included with your drive and plug it in to one of your USB Ports. When you have it in you're going to want to go to computer after you click on the Windows 7 oracle on the bottom left of your screen. You're going to want to double click on the disk in which has 0 memory used on it. And then open another thing in computers and open your main drive and drag everything you want to back up to the other drive. When your dad reinstalls ( resets ) windows, put in the drive once you have an anti-virus and everything running fine ( don't want to get viruses in case you moved a virus computer to computer ) and then drag it back to where it should be.