Note: This method is no longer recommended and only provided for compatibility reasons! See How to insert Euro symbol in LaTeX using UTF8 for the recommended method instead!
In order to insert the € symbol into your LaTeX document, first add
\usepackage[official]{eurosym}to the top of your document, e.g. directly after your \documentclass line.
After that, you can use
\euro{}to insert an € symbol anywhere in your document.