You should probably link us to the app you're going to be using on your mobile device, so we're able to see what your wallet is really like. I personally have never heard of it so I would recommend using a wallet from either Blockchain.info or BitGo (Little more on the experienced site for BitGo though)
You give the seller your ADDRESS from the bitcoin wallet when you go ahead and attempt to buy bitcoins, address' are used for pretty much everything on here when it comes to receiving bitcoin.
Spend two weeks reading as much as you can (in your free time) to educate yourself about Bitcoin, how it works, how to secure your private keys, etc., before you actually acquire any bitcoins.
If you do that well, you won't need to ask for any more advice.
The most important "rule" in my opinion: If you aren't the sole controller of your private keys, you don't have any bitcoins.
When you are confident that you can explain the above "rule", in detail, to someone else, then you might consider buying some bitcoins.
Going to have to fully agree with this though, if you don't really know how any of this works it's kind of waste and getting your coins stolen are probably going to be rather easy.
