Displaying forms 2&3 from a combo box on form 1

Question

I understand that my problem is probably really basic but any help would be greatly appreciated.  Anyway, I have form1, form2, and form3.  On form1 there is a combo box with two selectable values: form2 and form3.  How would I go about connecting the actual forms to the selectable values in the combo box, so that selecting a particular value will open the corresponding form?