First, are you really using this code in your template?
Code:
<fieldset style="margin-bottom: 6px; color: #333333;FONT: 11px Verdana, Tahoma;PADDING:3px;">
<legend><{$language[ticketdetails]}></legend><BR>
<{$language[articketid]}><{$ticket[fticketid]}><BR>
<{$language[ardepartment]}><{$ticket[department]}><BR>
<{$language[arpriority]}><font color="<{$priority[frcolorcode]}>"><{$ticket[priority]}></font><BR>
<{$language[arstatus]}><font color="<{$status[statuscolor]}>"><{$ticket[status]}></font><BR>
//My text here...
</fieldset>
If you are then remove the "//" before the text you are adding.
Also, you might want to make a container like this for your text.
Code:
<div class="mytext">My Text goes here...</div>
Or using a table:
Code:
<table width="100%" border="0" cellspacing="0" cellpadding="0" id="mytexttable">
<tr>
<td class="mytext">My Text goes here...</td>
</tr>
</table>
I have added the class so later you can style your text however you wish using the CSS in the Templates of your ADMIN.