CSS Formatting Issue

If you look at an event post:

https://edendayspa.com/2011/07/09/1165/

then the rest of the site, you will see that the plugin removes
some of the template formatting, eliminating the overall content
box.

Initially I was able at least to reduce my first problem by editing
events.css. At the time, the width was 100% and thus completely
out of range for the event post.

If you look at the event category listing:

https://edendayspa.com/category/events/

The formatting is again out of range and takes up the entire width
of the screen. How can I resolve this and get it into a normal content
box?

The theme editor suggested:

“I believe there is a spot in the settings for the plugin where you can add code before the calendar and after the calendar. If that’s the case, add this in the box for code before:”

<div id="content">

    <div id="top">
        <div id="top-content"></div>
    </div>

    <div id="middle" class="clearfix">
        <div id="middle-content">
            <div id="contentleft" class="clearfix">

and this in the box for code after:

        </div><!-- Close Middle Content -->
    </div><!-- Close Middle -->

    <div id="bottom"></div>

</div><!-- Close Content -->

Which would be great, if I knew precisely where it needed
to go. There is no plugin setting, like he thought, but can
this be added to any other code file?

Any help would be appreciated.

Thank you.