How to compare new value and old value in Sugar 7 Enterprise Process ?

Hello guys,

We have move Sugar 7 Pro to Sugar 7 Enterprise.

Now, we can use Process module instead of Workflow module.

This is Workflow, we need to migrate to Process (Opportunity Module):

1) "Opportunity" create/update Save .
2) Custom text field "Job no". If "job no" text field new value is not blank and old value is blank, We need to send e-mail notice.
How can I set Process and Process Business Rules?