The "Post Card" Effect
---It's a Clipping Mask!
Side Note: you can use this technique with any mono colored image, like a "fancy" brush or a Custom Shape...
Load your Candidate Photo and 'unlock it' by clicking on the padlock in the layer's palette
Roll Mouse over image to enlarge Select the type tool, choose a "FAT Font" and type...
If you select the "Move Tool" Key board short cut "v" and turn on (check) the Transform Control in the Move Tool's Option Bar 
you can re-size the text to fit the page by dragging on the corners of the transform area containing the text...
Did you unlock the main picture after you loaded it? After you write the text on top of the photo in a text layer, swap positions of the text and photo so the photo is the top layer and the text the bottom layer!
You can move layers up or down in the "stack" by holding down the left mouse button over the layer and dragging it up or down... That's why we need to unlock the layers. The photo will now hide the text!
Turn on clipping... It should not matter if the the top or bottom layer is highlighted. Hold down the option key (Mac) or Alt key (PC)
when the cursor changes between the layers, in the layer palette, click the mouse button once...
Or, Try the key board short cut Control G (PC) Command G (Mac)
Roll Mouse over image to enlarge
Or use the menu selection
Layer > Group with Previous
They all should do the same thing...
Notice how the thumbnail is now shifted to the right in the layers palette... and the background is now visible inside the text. The white and gray squares tell us that that area is transparent.
We are now going to add a text effect. For the text fx effects to work you need to select the text layer and choose an effect like drop shadow or outer glow
Some text effects however will turn off the clipping effect, so be careful! But, don't be afraid to experiment.
Roll Mouse over image to enlarge
I added two more things to the post card. A layer with the text "Tibet" and a background picture of the "Free" Tibet Flag. Note the order in the layers palette.
Have fun Clipping!