Hi @JeniyaKhatiwada
It is great that immersive reader has been made available on Canvas for you and other students. Unfortunately, the immersive reader will only be applicable for content created in Canvas, like pages, assignments etc. Here is a link with some more info.
If you would like to apply immersive reader to your class readings, perhaps you can check what format the document has been saved in (e.g. word/pdf) and view the accessibility options available in those apps. Microsoft has great accessibility tools, and adobe does too, but the document has be saved appropriately.
Check in with your teacher/s as well about how they can provide more accessible readings.
Thanks
Jen