How Do I: Run a class... Change at runtime?

Question

Hello:
 
I have the following lines to run a class for updated. I would like to change the name at runtime. Can someone tell me how?
 
ClassUpdateTest UpdateClass;
UpdateClass = new ClassUpdateTest(m_EventStopThread, m_EventThreadStopped, this);
UpdateClass.Run();
 
 
The "ClassUpdateTest"... I woulod like to change at run time. I have the value of it in a variable called textBoxUpdate.Text.