The code of a character is an ampersand (&) followed by its code, followed by a semicolon ( ; ). For instance to get the copyright symbol, you enter:
You'd write that all together without the plus signs, its just that this forum accepts the code and changes them so you can't see the code.
Which results in ©.
The code for the quotes he's referring to is ampersand, followed by the word "quot" and the semicolon. Just insert that and it will produce a quote that is automatically escaped in HTML. See:
"I used the code for quotes!"