To upload an .srt file in Canvas, go to My Media. Next to the video you would like to add captions to, click the greyed out pencil highlighted below with the red arrow.
You will then be on a screen with 9 options below your video, one of them is captions. Click captions
You will now see a blue button on the far left, “upload caption file”, click it.
Then a new box will pop up. Browse for the file. Select the language. And give it a label. If the language is English, “English” would be a good label. Then click save.