Which cables and housing do I need? I am going to build my own bike. I purchased the 105 5800 groupset the other day and was examining the different components.

The shifters came with some cables and cable housing. I have attached a pic of the cables and housing. As a newbie I can't tell what the cables and housing are for, ie are they both sufficient for the gears and brakes or do I need to purchase some extra? Can someone clarify for me please.

Much appreciated!
Those are just gear cables, you will need to buy brake cables and outers.

Good on you for building it yourself, it's definitely do-able with a modicum of skill and even with limited experience. But... there's quite a few things you can do slightly wrong that will make the bike unsafe to ride. I think it would be good to have someone check over the bike before you ride it. 

There are lots of online tutorials showing you how to install brake and gear cables, any search engine will find them for you (I couldn't find one using the search box on the top right of this page). Similarly for most of the other steps, and finding this site will hopefully help you with the other questions you'll inevitably come up with.

Also, it's probably worth reading some of the questions here about upgrading components and building from scratch, as it almost always works out more expensive than buying a whole bike, and can be hugely more expensive. Unless you work in a bike shop or can otherwise get new components at wholesale or better, it will be more expensive. That's especially true if you compare a second hand bike to buying new parts. Note that buying second hand parts to fit an existing bike is a fairly skilled task (you need to know how all the sizing works on the various parts as well as which parts will work with what you already have).