Paint.NET is free software for Windows computers. It edits image files. The software competes with professional solutions such as Adobe Photoshop as well as free software such as the Microsoft Paint application included with Windows. One of the things that you can do with Paint.NET is create an image with a transparent background–for example, an icon that blends with desktop wallpaper. Using Paint.Net, you can make the background layer of any image transparent by changing the layer's properties.
Launch Paint.NET and open the image file that you would like to modify.
Click "Background" in the Layers window on the right side of the screen. If you have closed the Layers window, click the "Window" drop-down menu at the top of the screen, and then click "Layers." Alternatively, press the "F7" key.
Click the "Layers" drop-down menu at the top of the screen, and then click "Layer Properties."
Drag the slider bar next to "Opacity" all the way to the left to make the background completely transparent. The number next to the slider bar should now be "0." Alternatively, drag the slider bar to a different position to make the background only partially transparent.
Click the drop-down menu next to "Mode" to select how the background layer should be blended with the layer above it. "Normal" simply blends the two layers together, while other selections produce artistic or unusual effects. Note that the blend mode does not matter if you made the background layer completely transparent in the previous step.
Click "OK" to return the main Paint.NET window, where you can save your work.