How to create whitespace in LaTeX?

\vspace{2cm} is usually good for these sorts of things; it will insert 2cm of vertical space. In certain situations (I forget exactly when) you need to use the starred version, \vspace*{2cm}. Obviously, adjust the length as necessary.

Try either \smallskip, \medskip or \bigskip. Or use \vspace.

\\ ends a line. If there is no line preceding it, you cannot end it either.

A simple hack for this (in situations where you cannot use \vspace, is to print one space character and then the new line: \ \\.