How do i merge two C# projects and run a form from one of them in the other?

Hey,

Im trying to run two C# projects (merge together) and then from the click of a button open up a form from the other project if that made sense.. so for example i have project 1 and project 2 i want to merge them together and then say in project one create a button that opens up a windows form that has been created in project 2?

Sorry im quite a newbie with all this :)

Thanks,

Mattlav