In most modern games, loose .dds files should be placed in a specific subdirectory within your game's Data folder (e.g., Data/Textures/Interface/ ).

To open and edit the file, you will need software that supports the format, such as:

Because this specific file is usually part of a larger mod or the base game's UI assets, you typically "download" it by getting the relevant mod from a community hub:

If your modified dialog box isn't showing up, ensure the image dimensions are a power of two (e.g., 512x512 or 1024x1024), as many engines will fail to load textures that don't meet this rule.