You could use a pattern. Assuming you want a horizontal or vertical pinstripe, this is very easy to do.
Create a new document. Set the size to how large you want each repeating portion of your pinstripe to be. Fill the layer with whatever background color you want, then create a stripe against the right edge of the canvas of the desired color and thickness.
Then go to Edit > Define Pattern (I think... don't have PS open at the moment), name the new pattern whatever you want, and hit OK.
Then go to the image you want the pattern in and deploy it using either the fill tool or in the target layer's blending options.