workflow "backpointers" in vTiger

I seem to have a basic misunderstanding about how to use workflow in vTiger. I'm a beginner, so that makes sense.

I've created some workflows in VTiger 7, and I'm able to create a task when a field on a Sales Order is updated. I want to be able to identify which sales order prompted the creation of that task, and it is key for the task to know which sales order prompted it's creation