You can probably get something like this.
http://www.bestbuy.ca/catalog/prodde...73&catid=20238
Most computers will have USB ports unless yours is from the last century. If you have anything that plugs into your computer (mouse/keyboard etc.) that looks like this plug pictured then you can buy a USB 2.0 Hard drive.
If your computer don't have enough USB ports you can buy a hub and connect everything to it then connect the hub to the computer:
http://www.bestbuy.ca/catalog/prodde...80&catid=20388
Happy shopping, Hope that helps.