Here are two different examples :
Okay let's get started !
Difficulty : Very Easy
1.) Open a picture that you want to transform
2.) Duplicate the background layer by right-clicking it and selecting "Duplicate layer..."
3.) Then create a new Layer and drag it between the background- and the new background-copy-layer
4.) Fill the new layer black with the Paint Bucket Tool (G)
5.) Create a text layer on the very top with the Text Tool (T) and instead of just clicking somewhere to write something , drag out a text area from the very far top left to the bottom right of the canvas.
6.) Fill up the whole area with text using a small font-size (Font-Color : White) and writing something related to the picture. For this example I'm gonna be pasting "Why so serious ?" all over because I use a picture with the Joker from Batman.
7.) This is how it should be looking by now :
(Notice how my text area barley exceeds the canvas borders ? That's so your text doesn't look so blocky and organized when pasting the same thing over and over. Try it out and you will see what I mean)
8.) We're almost done. Drag the Text-Layer under the background-copy layer now, select the background-copy go to the menu Layer > Create Clipping mask or simply hit CTRL+ALT+G and you are done !
You could now go and select your text-layer , hit CTRL+T to transform it and you could slightly rotate the text if you wanted, to add a nice little touch to it.
Until then, see you next time ;-)
Oh, in case you wonder what picture I have used : The picture is by Irina Bolshakova.