A completely view to integrate DB with a workflow build via Re-hosted designer

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WCF

WWF

Hello Experts
I'm working on an Archiving System.
Which I have to make for the user a tool to specify the Document-Life as a workflow. and then he just press run to be executed.

A scenario for example: a specify document goes to HR department then they check if its correct then sign it then send it to the Manager who sign it then save the document and the changes.

What I did till know is:
I read about WWF and Skelta then I decided to work with WWF. I Re-hosted WF Designer in WPF.
I know how to pass data In/Out workfow.

The data which the user must work on is in DB, so I have to integrate the workflow with DB. I read the best way is WCF.
I'm completely lost.
I know the output of a workflow not a console window is a lib.
but how can I make this via Re-Hosted designer which may just give me a XAML file.

So, I need to understand how I can integrate DB with a workflow build via Re-hosted designer.