Problem:

I have to customize a TFS2010 Build and I don't know Windows Workflow 4.0.

Solution:

I watched the following video to quickly bring me up to speed on Windows Workflow 4.0 and then I read the workflow of the default build template.

http://msmvps.com/blogs/theproblemsolver/archive/2009/12/08/online-wf4-presentation-recordings.aspx