"Many educators feel driven to create the “perfect” resources for their classes and it can be difficult put aside that perfection and use other people’s creations. However, the number, variety, and quality of OER available freely is such that any educator should be able to find resources they can readily (with or without adaptations) put to use within their classrooms. And adaptation or adoption of OER will almost always be more efficient than creating teaching materials from scratch." (Moist, 2017).
Start simple! Consider adding some open interactive elements from eCampusOntario's H5P Studio into a course, or look for an open textbook. Take a look at existing resources for an open textbook. There may be one that meets your needs without much tinkering required. If not, then consider adapting or creating an open textbook.