I have a question, I have to make a few programs for my class which I can't find decent documentation in my book for (ITT Tech, go figure)

Say I have my main form (Form1), when you press a button on form1, it opens a new form (form2) that has a text input box, you enter a number, it does its calculation and must send it's calculation to a label box in Form1. how do I do this? And does this work the same way for outputting it in a listbox (insted of a label box)?