Abbulix:

Masking
This tutorial will teach you the very basic concept of layer mask.
A layer mask, in a nutshell, is a way to hide some parts of a picture. In Photoshop, when using more than one layer for an image, using layer masks is a way to remove portions of the layers to "hide" them behind other portions of the image.
Now open a picture in Photoshop. I am using following picture for this tutorial it is taken from my own created wallpaper.
http://img185.exs.cx/img185/4681/sushmitaabb025xq.jpg



We need a duplicate layer, simply click layer>Duplicate Layer...
Then press OK




Now we have two layers



You can see "background copy" is showing selected. (the blue bar shows which layer is selected or current layer)
Now we will make an "A" on it by using text tool.



Doesn't matter what font and color you are using but must use big font size.



Now we have three layers and text layer is our current layer.



Click Layer>Layer Style>Stroke



Make changes as shown following picture then click OK



Now select background layer



Click Images>Adjustment>Hue/Saturation...
or press Ctrl+U



Make changes as shown following picture and press OK



Now hold "Background copy" layer and move it to top.



Be sure the text layer is between both pictures layers and background copy is the current layer.
Now we are ready to create clipping mask.
Click Layer>Create Clipping Mask or press Ctrl+G
And we done it. This is our final result.



If you don't want to use text, you can use different shapes as well.