Create text widget to use definition list

How can I modify the functions.php to produce a definition list with a text widget? What I’d like to produce in the sidebar is a list of events, with the event title using the dt element, with several dd elements for each dt. I tried editing the functions.php, but my efforts resulted in the dd enclosing the dt, with the div class textwidget code appearing after the dt elements.
What I want is for the user to have the option to add any number of events; there would always be at least one event in the sidebar. So the code produced in the sidebar would be:
‘<dl>
<dt>Event 1</dt>
<dd>Event 1 Date</dd>
<dd>Event 1 speaker</dd>
<dd>Event 1 description</dd>

<dt>Event 2</dt>
<dd>Event 2 Date</dd>
<dd>Event 2 speaker</dd>
<dd>Event 2 description</dd>
</dl>’