IPAD - How to write only in capital letters

I press the shift key on the keyboard of my iPad but it only works for the first letter, then change to lowercase. As I write fluently in capitals?   Solution What you have to do is double click on the Shift key (the one with the arrow), in this way block the shift key. If you do not work is because caps lock is off, to enable it: Go to "Settings> Generate> Keyboard" Click on