DO IT
1. Open file /templates/{current template}/css/engine.css
At the end of file, add
.popup {
    border: 1px solid #BEBEBE;
    color: #757575;
    font-size: 11px;
    font-family: tahoma;
    text-decoration: none;
    background-color: #FFFFD5;
}
.popup a:active, .popup a:visited, .popup a:link {
    color: #ee8013;
    text-decoration: none;
}
.popup a:hover {
    color: #0084ff;
    text-decoration: none;
}
.popup img {
    border:none;
}
    border: 1px solid #BEBEBE;
    color: #757575;
    font-size: 11px;
    font-family: tahoma;
    text-decoration: none;
    background-color: #FFFFD5;
}
.popup a:active, .popup a:visited, .popup a:link {
    color: #ee8013;
    text-decoration: none;
}
.popup a:hover {
    color: #0084ff;
    text-decoration: none;
}
.popup img {
    border:none;
}
2. Save file
to folder /templates/{current template}/images3. Open file /templates/{current template}/main.tpl
Find
{AJAX}
BELOW add
[group=5]
<table class="popup" style="width: 100%; z-index: 1; height: 25px; position: fixed; top: 1px; left: 1px; right: 1px" cellspacing="0" cellpadding="0">
<tr>
<td ><img alt="" src="{THEME}/images/noaccess.gif"><span><strong>Welcome Guest ! </strong> Please <a href="/index.php?do=register">REGISTER</a> to view full article and post new article</span> </td>
</tr>
</table>
[/group]
<table class="popup" style="width: 100%; z-index: 1; height: 25px; position: fixed; top: 1px; left: 1px; right: 1px" cellspacing="0" cellpadding="0">
<tr>
<td ><img alt="" src="{THEME}/images/noaccess.gif"><span><strong>Welcome Guest ! </strong> Please <a href="/index.php?do=register">REGISTER</a> to view full article and post new article</span> </td>
</tr>
</table>
[/group]
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