Put nikon d3100 slr camera pictures onto computer?

I just got a nikon d3100 slr camera and I want to know how to put the pictures onto the computer. No USB cables or anything came with it, so I'm wondering, do I have to purchase one?

You can purchace a USB cable, but it is better to get a cheap SD card reader. That will transfer all the pictures and video much faster, safer, and easier than connecting your camera to the computer and doing it that way.

For nearly a decade users of digital SLR cameras have used card readers. They are faster and allow the camera to be used while one card is being copied to the computer,

If your computer does not have a card reader, you can buy a USB 2.0 card reader for under $10

This is what should have come in the box

EN-EL14 Battery
MH-24 Battery Charger
DK-5 Eyepiece Cap
DK-20 Rubber Eyecap
AN-DC3 Camera Strap
BS-1 Accessory Shoe Cover
BF-1B Body Cap
ViewNX 2 CD-ROM

I just bought a D3100 as well and without reading anything i looked at the pictures of the quick setup guide and it (very blatently) explains to you that you will need to go out and buy a cord to transfer the photos i your computer doesn't have an internal card reader.
like the answers above me pointed out, buying a card reader instead of a cord would be a much better option.
i didn't think anyone could possibly be worse than myself at following directions, and i don't even read.

You should go with ABC Products® USB Cable

ABC Products® replacement for Nikon Part Numbers UC-E4 and UC-E5
10 year warranty
® ABC Products is a Registered Trade Mark