How to change background color in the Notepad++ text editor?

Go to Settings -> Style Configurator

Select Theme: Choose whichever you like best (the top two are easiest to read by most people's preference)

You may need admin access to do it on your system.

1. Create a folder 'themes' in the Notepad++ installation folder i.e. C:\Program Files (x86)\Notepad++
2. Search or visit pages like http://timtrott.co.uk/notepad-colour-schemes/ to download the favourite theme. It will be an XML file.
   • Note: I prefer Neon any day.
3. Download the themes from the site and drag them to the themes folder.
   • Note: I was unable to copy-paste or create new files in 'themes' folder so I used drag and that worked.
4. Follow the steps provided by @triforceofcourage to select the new theme in Notepad++ preferences.