After reading Pioneer Woman's Photography post about making an image with rounded corners, I thought I would go over using a clipping mask one more time.
This concept is great because it uses non-destructive editing.
Here is one I made with an image of little Miss G.
I used PW's Lovely & Ethereal and her Seventies action on the image.
I used the rounded rectangle shape and made my shape. Distressed the edges, then saved it as a png file.
From the bottom layer going up....
You will have your background color, lets say white.
Then you add your mask to the next layer up.
Then your image goes on top.
You can clip your image and mask together a couple of ways.
Highlight your image layer. Hold down the alt key and click on the line between the image layer and the mask. Find that difficult? Go to Layer, Group with Previous. (top tool bar)
After your image is clipped, you can move it around or resize it as you like. But you image stays in it's original condition. Hence non-destructive editing. =)
Hope you try making your own!!
If you still need more help. Scroll way down and I have a screen shot. The post was labeled "Freebie time".