To enable linking, embedding and attaching files within other drupal content you need to navigate to the administration settings pages and access the dbFM Main Settings (admin/settings/dbfm) :
You can use the 'Activate dbfm on specific page type' textbox to control which content types are allowed to use dbFM. In the example above ALL node types with a textedit area (in either 'add' or 'edit' modes) will display an icon under the text area. Pressing the icon will launch a popup containing the dbFM browser. You can restrict the content types that are allowed to use dbFM - for example, just having an entry of 'blog/*' would restrict the use of dbFM to blog nodes (this area needs a little work - although dbFM will not launch on other node types the icon still appears but is inactive).
Attachments require further activation. Navigate to Administer - Content Management - Content Types (admin/content/types) and select the content type you with to use attachments with: