Update Form From Wizard

I have some experience with C++ VS6. We are currently migrating to C# .net. I am trying to create a wizard which when changed automatically updates the control on the main form. Here's my problem. I have created a control which consists of 3 combo boxes. I load the control to the main form with no problem. When the wizard button is clicked my wizard form appears with an instance of the same combo box as the main form. I cannot figure out how to get the combo box on the main form to update with the selection from the combo box on the wizard form. Can somebody help??