Collect extra field to display the top of detail

Collect extra field to display the top of the detail page.

hello,
I am a beginner in php and mysql.
In the admin OSProperty, I created an extra field "available" with two choices "now" or "to be agreed".
I would like to edit the field to show at the top of the page (see picture attached)

After the lines in the file details.html.tpl.php "blue theme"

<ul class = "attribute-list">
<? php
if ($ row-> ref! = "") {
I need regular.>
<li> <strong> R & eacute; f: </ strong> <span> ref;> </ span> </ li> <? php echo $ row-?>?
<? php}?>
<li> <strong> <? php echo JText :: _ ('os_type')?> </ strong> <span> type_name> </ span> </ li> <? php echo $ row-?>?
<li> <strong> <? php echo JText :: _ ('OS_CATEGORY')?> </ strong> <span> category_name> </ span> </ li> <? php echo $ row-?>?

I added the line

<li> <strong> <? php echo JText :: _ ('Available')?> <? php echo $ row->? </ strong> <span> field_option> </ span> </ li>

No results are displayed. Who can help me?

thank you.