$post should be a post ID (so $post->ID if you’ve got the global $post object in scope)
the function call parameters are:
$id: the id of the post (integer)
$keyname: a string containing the name of the custom field
$single: boolean – true means return a string for the first value, false means an array of all values for the key
The codex page is here: http://codex.wordpress.org/Function_Reference/get_post_meta
You can also try get_post_custom_values($key, $post_id)
Where $key is the ‘name’ of the custom field you want to retrieve. $post_id is optional, and defaults to the current post.