You have two choices:
1) Set up an SQL Receive Port – the data retrieved will activate the orchestration with the activating receive (first receive at top of orchestration). This port would poll every x seconds (or minutes).
So you would need to delete the data or flag the data as being already processed so the same data doesn’t reprocess every time the polling intervals comes around again.
2) Set up a Send Port (request/response) – You receive some other message that starts your orchestration, then you call the stored proc by doing a send/receive to this send port.
Perhaps this helps, or you can describe more fully what it is you are trying to do.
I have full video examples available at site below.