Here's a basic PowerPoint template that you can use to create your webinar.
I often just use a white background slides, or white-background with a banner on top (and bottom at times).
See two examples below - feel free to modify and use for yourself:
To save the templates to your computer,RIGHT CLICK on the above links, then choose SAVE AS!
* Do NOT use the images shown in the samples! Always make sure to own the rights to the images you use!