In previous versions of Android, it was necessary to download an application to capture mobile screen.
In the model that comes with Sony Xperia SP version, this functionality is already built into the system.
To make screenshot, simply simultaneously press the power key and the volume down key:
and you're done!
To view the image, just display the notification area, sliding your finger from the top down. In the notification area the message "Screenshot captured" should appear. Clicking on the message, we can open the image with the "Album" application, and from there we can send it using any of the applications you have installed: Facebook, Twitter, MMS, Gmail, ...)