Drawing lessons and trademarks

Hi everyone!

I am currently building a website about drawing cartoons. I would really like to create a section about drawing famous characters. Of course, these characters are copyrighted and do have trademarks.

My question is:

Is it legal (or part of freedom of speech) to offer free drawing lessons of famous cartoon characters on my site. When I say free, I mean that the visitor doesn't have to pay to view the lesson itself. But of course, some google adsense ads or affiliate links can be visible on the page.

Thanks a lot for your time! I really appreciate it!