How to add edit button in content type?
You actually need to add the edit button in a node. well, first you need to get the node ID, create template.php and add this function :

function YOUR-THEME_preprocess_node(&amp;$variables)
{
    if (isset($variables['node'])) 
    {
         $variables['id'] = $variables['node']-&gt;nid;
    }
}


in this way the node id will be saved in the $id variable inside the node template file. if you want to use the default node.tpl.php copy this file from modules/system/node.tpl.php. now add this code where ever you want in the new copied node.tpl.php

&lt;?php
    global $base_url;
?&gt;
&lt;a href="&lt;?php print $base_url;?&gt;/node/&lt;?php print $id;?&gt;/edit"&gt;Edit the Content! &lt;/a&gt;


if you suggest any theme hook (theme the node page) no difference does it make, use the above code, the link always will be 

"&lt;?php print $base_url;?&gt;/node/&lt;?php print $id;?&gt;/edit"


Good luck