Hello,
Code for adding a position is:
<jdoc:include type="modules" name="nameofposition" style="xhtml" />
You can wrap it in an div to style it individually, or you can give it special style by adding class suffix to module published in that position.
<div class="someclass">
<jdoc:include type="modules" name="name-of-position" style="xhtml" />
</div>
To find the new position in dropdown list, add it to file templateDetails.xml
The file you have to add the position to depends on what layout you use.
Take a look in directory template/layouts, open the layout you use and find the location in the code where you want to add a position.
good luck,
Micrantha