passing data between forms

Question

Hi, I have 2 child forms inside an MDI form. On the first form is a search button that will launch the search form also inside the mdi form. when I doubleclick the listview control I want the text on the listview control copied on the first form searchtextbox so i can perform the process with it. How can I launch the 2nd form inside the MDI form and how can I pass the data from the second form back to the first form? Thanks