You can easily customize your slides by following these steps provided by Microsoft Support :
: Use a maximum of six bullets per slide with six words in each bullet to avoid information overload. Powerpoint Presentations Backgrounds
Click to upload an image from your device or browse stock images. You can easily customize your slides by following
: Great for creative or "edgy" presentations that need a bit of visual flair without being distracting. Powerpoint Presentations Backgrounds
Right-click the margin of your slide and select . Choose Picture or texture fill .