Though you can always choose a premade template, you may want to customize your PowerPoint ... the "Format Background" menu by right-clicking or selecting the option in the "Design" tab at the ...

You can change the background to anything you like if you're using Powerpoint to create presentations ... Step 2: Select Design in the top-menu bar. You can also adjust the transparency using ...

Launch Microsoft PowerPoint, and open the PPTX file for which you want to use a GIF as the background. Select the appropriate slide. Click the "Design" tab, and locate the "Background" section.