if you want all pics to be the same width or height, some very simple steps:
say you have a bunch of pics with more or less the same dimensions. then open a pic (it will be easier if it's the bigger pic you have), go to the actions screen and start recording an action. first create a new layer--> fill it with black (or whatever color you want for the border) --> send this layer to bg --> press X (this will change between bg and foreground colors) --> new canvas size (choose the size you want for all pics) and you're done
Bow you must save, you can save the pics as is (not recommended), save as... or do it my way: save for web, choose an appropriate rez (as default, I use JPEG 51 res) and then save WITHOUT CHANGING THE NAME but in a different folder, so you can go back if you made a mistake. Done? close image and stop recording action. Now you have an action you can use for your pics
If your interest is not changing sizes, but only having a border, just open pic, record action, new layer--> fill with a different color than the one you want for your border (ie, if border will be red, you can fill with black or white) --> choose border color-->stroke (select width here)-->choose the magic eraser tool--> erase the non-border color and now you see your image with a border. Save using the methods above, close image, stop recording.
Hope it helps
