In the dialog box, select the set and the action you just created under the "Play" section.
For the source, choose Folder then click "Choose…" to browse to the folder that contains the images you want to process.
For the destination, choose Folder and browse to a different folder for Photoshop to output the resized images.
Note: You can choose "None" or "Save and Close" to have Photoshop save them in the source folder, but I don't advise it. It's too easy to make a mistake and overwrite your original files. Once, you're sure your batch processing was successful, you can relocate the files if you desire.
Be sure to check the box for Override Action “Save As” Commands so that your new files will be saved without prompting. (You can read more about this option in Photoshop Help under Automating tasks > Processing a batch of files > Batch and droplet processing options.)
In the file naming section, you can choose how you want your files to be named. In my screen shot, you can see, I am appending "-800x600" to the original document name. You can use the pull down menus to select pre-defined data for these fields, or type directly into the fields.
For errors you can either have the batch process stop, or create a log file of the errors.
After setting your options, click OK, then sit back and watch as Photoshop does all the work for you! Once you have an action and you know how to use the batch command, you can use it anytime you have several photos you need to resize. You could even do an another action to rotate a folder of images, or perform any other image processing that you normally do manually.
