Use the panel for layout with multiple columns I created my own content type. I would like to further customize it by adding columns. I installed the module panel. Can I use the same panel layout to include my content type? Also, how do I put a picture in a field of the panel?
I would use panels for layout of a page which contains various bits and pieces from other pages. For layout of the display of a single page or node type I would edit the templates page--content-type.tpl.php and node--content-type.tpl.php.

In node--content-type.tpl.php you could then do something like:

&lt;div class="col1"&gt;
&lt;?php
  // Hide fields so that we can render them later.
  hide($content['field_image_main']);
  print render($content); 
?&gt;
&lt;/div&gt;
&lt;div class="col2"&gt;
  &lt;?php print render($content['field_image_main']);?&gt;
&lt;/div&gt;