RECOMMENDED:
   First, back up your Stardew Valley\Content\Portraits\ folder!
   You can do this by simply copying it to a different folder.

INSTALLATION:
   Extract files into your main Stardew Valley directory. For steam installs, this is by default:
      C:\Program Files\Steam\steamapps\common\Stardew Valley\

   If you install to the correct directory, the files will be merged into the correct folder.
   Select 'yes' for any file overwrite prompts.

if you have SVE mod, you have to replace the picture:
      Stardew Valley\mods\Stardew Valley Expanded\[CP] Stardew Valley Expanded\assets\CharacterFiles\Portraits\Sandy\

UNINSTALLATION:
   Delete your Stardew Valley\Content\Portraits folder.
   Restore your backup!
       If you did not make a backup, you can have steam "Verify the integrity of your game cache," but this may
       remove other mods as well.