You're jumping in a few steps deep, here's a quick quiz:
There are calculators around the web, that will help you predict, based on your hashing power, how much that hashing power will return.
This is not considering electricity costs, maintenance fees. This will also not consider mining fees and the payment structure if you use a pool or service.
My understanding is that CEX.io is not a good price for the power you get, and that there is some controversy around the actual pool that you're subscribing to, ghash.io. As far as I'm aware, mining returns require a lot of cash investment up front and still take a long time to return, if at all. That cash would be better spent simply buying the bitcoin. You could get a set of the low end asic miners
http://www.ebay.com/itm/9-X-Block-Erupter-USB-Asic-Miner-Mine-Bitcoin-3GH-S-total-/271326536366?pt=LH_DefaultDomain_0&hash=item3f2c5262ae (random link no idea if this is a good deal or who's it is, not mine) and use that as a starting point to see, with the aforementioned tools, what your ROI would be and when you could expect - if ever - to gain it. It will grant you some coins, so you could potentially invest at exchanges and play day trader a little bit. But probably not enough to purchase anything any time soon. Of course all of this investment asserts guessing at future bitcoin value. If it goes up x10,000,000,000,000 then sure even the worst investments now are huge winners and being more careful with costs doesn't matter.
Quiz over. Do you understand everything I said? If not, read around the web until you do. Do you want to "invest" or is this an endeavor to fortify bitcoins (or a little of both?) There is a lot to learn about why it is valuable, how it works, and the various industries around them.