where can I learn about differential forms, what they represent and how to integrate them.
PS: Where can I read about vectorial spaces and vectorial analysis, especially how to integrate.
I need these to understand my physics course, classical mechanics.
There are plenty of books about differential forms and each of us will have a personal favourite. If you are starting out, I would suggest maybe having a look at:
Hopefully one of those will have what you need. I am sure there are also plenty of notes you could find online that cover similar material.