There are a few ways to upload actions to Photoshop. The easiest way is to use the File > Upload to Photoshop menu item. You can also use the keyboard shortcut Cmd-U (or Command-U on a Mac). If you want to upload an action that is specific to Photoshop, you can create a file called “actions.psd” and save it in the same folder as your Photoshop files. Then, when you open a file that contains an action from this file, Photoshop will automatically load the action and start working on it.
