Vista - Sequence of steps using workflow foundation in ASP.NET

Hi,

I started to know about WF in ASP.NET when I looked into
http://www.masteringbiztalk.com/atlasworkflowdesigner

I have a similar requirement. My objective is that I need to have
similar UI. But I need to have an execute button which will do some
processing based on the workflow generated using drag and drop. How
can I do that ? I mean, is the workflow saved somewhere where from I
can parse it and fire different tasks based on the activity sequence ?

Is it necessary to use database to save the workflow ? Can't I use an
xml file ?

Achintya