First things first, if you want to join Bitcoin, you need a Bitcoin wallet. That is where whatever you earn go, and what you can use to do payments.
This list will very likely be expanded.
Carteras de Bitcoin en línea
This is the most popular Online Bitcoin wallet. Here you just create an account, and once you create it and log in (and verify your e-mail and all that), simply go to “Receive” and it will give you a Bitcoin address and a QR code for that address.
And then you get your Bitcoin address and a QR code that can be scanned.
Carteras de Bitcoin en tu teléfono
Another alternative is to use a Bitcoin wallet in your mobile phone, the one I use is mycellium. In the Google Play store it is the alternative with the most stars. It is solid and simple to use. You also get a bitcoin address and a QR code that you can use to receive Bitcoins.
If you are trying to send, it gives you the option to scan a QR code
Mycelium in the Google Play Store
One is of course using the actual Bitcoin Core, this is a full Bitcoin node, this is what makes the currency work and be desentralized. Running the node means that you have the data of every Bitcoin transaction that has ever been done. At the writing of this article having the full node takes 104,6 GiB (112 325 029 845 bytes). Setting it up is easy, but it takes a very long time to download and verify every transaction in the history of Bitcoin. You have been warned. Still, with this you are in complete control of your Bitcoins.
It has an option where it allows you to ask for payments, doing this will generate you a new address (you can also use an existing one but it is highly recommended to use one address for every thing so you are not so easily tracked).
Another option is Electrum. You have the wallet, but they run the full node and have the blockchain so you don’t have to do it yourself, it becomes very light and very fast.