Hi,

how to properly use quotation marks and the surrounding punctuation and capital letters?

Many people will reply like this:/, "One plus One is two. It's just that simple!"
John said,/: "where are you?"
The text book says:/, "Five-hundred dollars is a lot of money."
The Bible says:/, "He who has an ear...." (Revalation)

I asked: "Is one plus one equal to two?" he replied: "Yes."

You can find in books a lot of very precise rules about punctuation in tricky situations. However, as just a normal everyday English speaker/writer, I would write these things like this.

Many people will reply like this: "One plus one is two. It's just that simple!"
John said "Where are you?"
The text book says "Five hundred dollars is a lot of money."
The Bible says "He who has an ear...." (Revelations).

I asked "Is one plus one equal to two?" and he replied "Yes."

Double quotes are OK, but I usually use single quotes.

Best wishes, Clive