You may already provide students with your static PowerPoint presentations in the File section of your course. To make this content more engaging, you could take that same PowerPoint file and narrate the slides. It may be best to break up long slide decks into smaller files so you have shorter videos that are no longer than 10 minutes.
To add recordings to each slide (1) click the Slideshow tab. Select Record Slide Show. Select the desired option and start recording. If you record each slide separately and you mess up on a slide, just start over recording the audio for that slide. Continue this process until all your slides have an audio file. Be sure to save often. (2) You can test your timings by clicking Rehearse Timings.
Once finished, then you could convert the PowerPoint to a video file and upload it Canvas. In PowerPoint click File to view the Backstage. (1) Click Export. (2) On the Export screen select Create Video. (3) Choose Internet Quality and Use Recorded Timings and Narration. (4) Click Create Video. The process of creating the video will take some time so be patient as PowerPoint creates your file. Once your file is created, use the media comment tool in the rich content editor to upload the video to your Canvas course. Don't forget to caption your video once you have upload it to Canvas.