In the last semester I had Vector Analysis lecture. We have seen about some basic geometry of sphere, then we got into basics if vectors that we seen in first semester in mechanics lecture but this was more like linear algebra. Then I learned about lines and planes. Then we have seen about partial derivative, double integrals, triple integrals, scalar field, vector field, gradient vector, divergence of a scalar and vector fields, rotations of vector fields, curl of vector fields, line integrals and so on.
Due to covid-19 I couldn't be able to learn and understand the topics I have seen in the lecture. Also I'm interested in these divergence, curl, rotation and vector fields topics. I want to learn them all from zero. I need your online resource recommendation. If you can recommend me PDF file, it could be very helpful. (I like demonstrations and illustrations of vector analysis. If the PDF has good illustrations, I would be very happy)
I know two good courses on this topic that could help you to visualize the demonstrations and illustrate them. A good start is the Vector Calculus for Engineers available on Coursera. The other one is the Multivariable Calculus available on Mit opencourseware. Both of them will give you the tools that you are looking for.