Step one: download and save the actions set in an accessible place.
Step two: in photoshop, press alt+F9 to open the action window if it is not already displayed.
Step three: in the upper right hand corner of the action window there is a small circle with an arrow. press on the arrow to reveal a panel of options. select "Load Actions". open the action set you've saved.
Step four: the action window should now have this action set displayed below the default actions. find the action you want to use.
Step five: to play the action, simply select it by name and press play. the action will play to the end, at which point you can edit anything you like.
Making an action:
Step one: open the image you want to use to create the action.
Step two: find the icon on the bottom of the action window directly to the left of the trash can. that will create a new action. give the action a name and press OK. you will now be recording.
Step three: begin making actions such as "new fill layer," "new adjustment layer," and so on. If you make a mistake and want to delete anything, press the stop playing/recording button and select the step you do not want, press the delete icon. then simply press record to begin recording again.
Step four: once you've finished all the steps you want in the action, you can press stop recording/playing. to make sure you save the action, select the set name (Default Actions, dusty_memories actions, etc.) go into the action option menu and select save actions.