Hi everybody! I need some help!!

I created a custom entity on my CRM 3.0 Server, called "PosVenda". I
also created some custom fields and a relationship with the Opportunity
entity. It's working fine. But now, I need to create a workflow rule,
that fires when an Opportunity is closed (Won), and creates a
"PosVenda".
I'm trying now to create a Workflow .NET assembly, to do this action.

But the question is: How can I use CRM classes to create a new
"PosVenda"?

Thanks a lot for your help!!

[]'s
Nando