Watch this! It's funny and will teach you something!
Use the notes part of PowerPoint to help you remember what to say. Here's an example of how you can communicate information more effectively so that your audience will remember it!
Way to many words!
Use pictures for the most important information.
Since you will need images, you need to know how to search for images that are free for you to use. Many images are licensed under something called "Creative Commons" which for your purpose in a public education setting, they are free to use, and only some of them require you to attribute the work to the author/owner. Here are some links for searching pictures licensed under Creative Commons.
Overlay an imaginary 3x3 grid on top of your slide.
At the intersections, put the key points.
Notice as you watch these that not all of the words are on the slides, but that the presenters provide an image and a few words that tell a story. All of the presentations are pretty long; you don't have to watch them all, but the first one gives some great tips for using PowerPoint effectively!