I am trying to create a building block to log users into external systems, so they wont have to log in multiple times. The idea is to have a link with query string parameters that will let the building block know what application the user is trying to log into. I need to know the username and ID of the user so I can encrypt the data and go through the steps the app requires I have code in a .NET app that does this, I just need to move this to a building block). I haven't built a building block before so where would be a good place to start? How can I get the username and ID of the person who is currently logged in? Any help would be appreciated. Thanks in advance.