The edge of the crucible when in the vertical position must line up with the inside of the flask hole.
Acu-Pour 2 - Attachment of the Pouring Handle
Not a great video but still easy to follow
Professional Kit - Product Information
If you have purchased this kit here is a video about it.
Using the Crucible
Heat the crucible first before adding the metal. If hot or humid out then the flux surface may be sticky causing it to bubble. Once it bubbles and stops than add your metal. Over time, the surface may become dark which is OK and nothing to worry about.
Prepping the Clay
Break it up and remove the clumps. Also, keep it in the bag so that it stays clean. Discard the burnt clay that forms after pouring.