Thanks for the purchase! The file contains both PSD and JPEG files for the variety of working options you can use. 

In order to edit the PSD file, you need to double-click "Edit Content" layer's thumbnail (marked with green), delete the Delete Me layer, then add your own graphics. After that, press Cmd+S to save the adjustments to simply close the tab and in the appeared window click "Save".

For any additional guidance, please get in touch via info@pixelbuddha.net 

Thanks, 
Pixelbuddha & DesignSquad