Placing Test Behind an Object

Today I learnt how to use layer masks in Photoshop as I wanted to place a portion of text behind an image. This is a method of hiding pixels used when you want to alter certain portions of an image rather than delete the other bits. This was you don't destroy your original image and your picture remains flexible enabling you to experiment until you achieve the desired effect.

For the step by step approach look to this address  Placing Text Behind an Object.