changing the colour dependant on an If statement

firstly sorry if this is a stupid question but her goes.... I am trying create a change of colour based on a $_session variable like this

            <li>             
              <fieldset>
                <?php

                if ($_SESSION['Question1Answer'] != '1C') {
                    <?php fieldset id="incorrect" />
                    echo "Q1. When was barb wire patented.";
                    echo "The Correct answer is 1874";
                }
                    <?php fieldset id="correct" />
                ?>
              </fieldset>                   
            </li>

then in the style sheet I have #incorrect { color: red; border: medium; } #correct { color: green; border: thin; }

Does any one know what I am doing wrong please ?