Help with CSS and profile fields...

[JMEWLS`]

Basically, I want to add a profile field that allows you the users to choose the background of the webpage. I'm currently using profile field 6.. I edited the vbulletin.css template and replace this:

    background:{vb:stylevar doc_background};
    <vb:if condition="is_browser('opera') && $stylevar['textdirection'] == 'rtl'">
        overflow-x: hidden;
    </vb:if>

With this:

    background:{ background-attachment:fixed; background-repeat:repeat; background-image:<vb:if condition="$post['field6']">
{vb:raw post.field6}</vb:if>};
    <vb:if condition="is_browser('opera') && $stylevar['textdirection'] == 'rtl'">
        overflow-x: hidden;
    </vb:if></style>

In the profile fields I'm using a single line text box.