Navigation problems

Hi All.

I just started Wd4a about a week back.

I am making an application in which navigation has to be like this :

View 1 to View 3 and back to View 1.

View 2 to View 3 and back to View 2.

Now, my problem is View 3 has one button Back which should take it to the view from which it came, i.e. if it came from View 1, go back to View 1 and if it came from View 2, go back to VIew 2.

How do I know which view it came from?

Another thing, can someone please give me an example of how to pass parameters via events?

I see that when I create an action, there is a check box to transfer UI elements. What's that for, i don't understand. Can someone please elaborate on it?

Thanks for your time to read and reply to my petty queries.