If you’re new to KDE4 or KDE for that matter, you might be a little bit lost in trying to customize it, especially when it comes to themes and wallpapers. Here’s how you can change them.
Right-click on the desktop and left-click “Desktop Activity”

Desktop settings opens up.

From the above screenshot – you’ll see two options – open, and Get New Wallpapers. By clicking on Open you can browser to the directory where all your images are stored, select it and set it as your wallpaper.

Once you’re chosen your required wallpaper, hit apply, and your selected image will be set as the wallpaper.

If you don’t have too many wallpapers on your system, or prefer getting some excellent wallpapers from outside sources, KDE4 provides a neat way to get and install them. At the Desktop Settings screen, click on the Get New Wallpapers button.

You’ll get the Plasma Addon installer screen. The screen gives you various options to get your desired wallpaper. You can sort by highest ratings, downloads, most popular, or just enter a search criteria of your own. Once you’ve selected your wallpaper, just click on the Install button, and the wallpaper will be ready to be installed.
Hit the close button to head back to the previous screen. You’ll see that the wallpaper is available, just select it, and hit Apply. Your new wallpaper is ready!

Let us have a look at how you can change themes. Like wallpapers, you can change themes by downloading from the Internet or by using the Get Hot New Stuff interface. We’ll use the Get Hot New Stuff interface. The screen for changing themes is a bit hidden, we’ll have to goto Desktop settings (read: Personal Settings / Configure Desktop) first. Once there, click on Appearance.

Once in Appearance, click on Styles and Workspace tab. Then proceed to click on Get New Themes.

Select a theme which you like, and click on the install button. Then click on close to go back to the theme selection screen. Click on the theme and click Apply. That’s it, your new theme is installed!
If you want to change individual aspects of the theme, mix and match best elements of multiple themes, head back to Personal Settings, and click on the Advanced tab, and from there select Desktop Theme details

Once in, mix and match and customize till you’re happy with the final results!

