make checkbox checked

[Evil X]

how do I make a checkbox checked by default

PHP Code:

<if condition="$show['vbookieevent']">
                <fieldset class="fieldset">
                    <legend>$vbphrase[post_a_vbookieevent]</legend>
                    <div style="padding:$stylevar[formspacer]px">

                        <div><label for="cb_postvbookieevent"><input type="checkbox" name="postvbookieevent" value="yes" id="cb_postvbookieevent" tabindex="1" $checked[postvbookieevent] />$vbphrase[yes_post_a_vbookieevent_thread]</label></div>

                    </div>
                </fieldset>
                </if>