First install and enable the devel module as it makes the process of looking at the $node object a lot easier.
Make sure you have a node.tpl.php in your theme (You can create your own node-my-content-type-name.tpl.php also but in D6 you need to have a node.tpl.php to make this work).
At the top of the node.tpl or your own tpl file add.
you can then easily traverse the object/array. you can also use dpm($node). Remember if you exclude the $content variable any new fields that are added to your content type won't be output unless you specifically output them in your tpl. In D7 this has changed as you can use: