Yeah thats the RAM (memory). It can only fit into the memory slot one way round. Both RAM sticks will need to go into the same colour memory slots (ie both in blue or both in white). As above look at you manual to find out which ones they should be in (blue or white).
Most reliable place to find it is in the motherboard manual! Magnifying glass? look for manual on Gigabytes website and zoom in?
Here you go. Just make sure its the same motherboard.
Bottom of page 16 for your reference. BOTH IN EITHER BLUE OR WHITE.
I'm just about to connect the hard drive but it doesn't seem to have came with a SATA cable as the CD/DVDRW did (hard drive was the only thing that didn't come in a box) and it came in bubble wrap. with no cable. have they forgot to put it in?