Could you help me about integration?

Hello

I recently studied about mathcad through book named "Essential PTC mathcad Prime 3.0"

I saw half of the book becasue I felt get experience that I need to study basic thing.

Although I studied for a week about basic, I couldn't understand "integration"

so I want to get advice.

And I wonder that it is possible to change "range" to "vector" about all my work.

I guess to need to change "range" to "vector" in order to finish my work.