To use Microsoft Designer you simply log-in then choose the type of project you're designing (social media post, slides, or other). Then you state the goal of your project. Finally, upload a picture to use in your design and Microsoft Designer will generate a bunch of graphic designs for you. Watch my short vide that is embedded below to see how Microsoft Designer works.
Video - How to Use Microsoft Designer
Applications for Education
Microsoft Designer could be a good tool for improving your own graphics to use in your classroom handouts. It could also be a great way for students to improve their own graphics much like the PowerPoint design suggestions do.