Recently I came accors this amazing course in storytelling offered for free at Khan academy by Pixar - I can highly recommend it :)

It is not very time demanding and it comes with short engaging videos, a lot of examples from animated movies and a lot of practical tasks

Keep in mind: while it teaches you also about storytelling in general, it is primarily focused on visual storytelling

https://www.khanacademy.org/computing/pixar

@iynna I saw that you are interested in the topic of storytelling so you might want to check it out :)