Create a front end edit button for custom post types

I'm trying to create a front end edit link for a custom post type. I'm using Download manager . Can anyone help? I've manage to put the edit code <?php edit_post_link(); ?> in the single post template content-download-pa-single.php but the edit link jumps to the page editor in the backend. I want to edit the custom post entry. I tried putting this code in <?php edit_dlm_download_link(); ?> but it breaks the page. Do I need to register the custom post type for editing in the functions.php - if so, what would the code be?

Many thanks

Gordon