How to get the running instance of the object at runtime.

Question

I have created a sample windows application(SampApp) in C# and also created one automation application(AutoApp). I want to get the instance of some object that is running in SampApp in AutoApp. so that from AutoApp I should be able to send some data to SamApp object and do some operation at run time in SampApp. I launch SampApp in a seperate thread from AutoApp automation application, The issue I am facing here is that I am not able to get the controls to which I want to fill some data, in the invoked app SampApp. This I am doing enroute testing the feasability of automatiion testing for our application. Could you please help me on this? Thanks, Santosh.