RAM help

[pevergreen]

Alright, going to be purchasing stuff for my computer soon, and I'm in a bit of a confused state.

This is most likely the motherboard im going with : (Gigabyte GA-P55-UD6)
Its got the 6 ram slots, and its in dual channel format, I believe.
(# 6 x 1.5V DDR3 DIMM sockets supporting up to 16 GB of system memory
# Dual channel memory architecture )

My question is, I must fill the 4 blue sockets with the same size and same speed of RAM, but what goes into the 3rd and 6th slots?

Lets say I buy this: Corsair HX3X12G1600C9 12GB (6x XMS3 2GB) PC-12800 (1600MHz)

Would I be able to just put all those in and have it work?

thanks,
pever.