Help me in how to pass values between forms

Question

Hi every body ; i have aproblem in passing values between forms ;i will dicuss the case in simple : 1- created new application with form1 contains only one button 2- in button click event created two instances of form2 and form3 which i add them in the project 3- form2 called f2 in instance contains a textbox 4- form3 called f3 in instance contains numeric up down control 5- when i press button in form1 then form2 f2 and form3 f3 will be shown 6- all i want to do that when i press numeric up or numeric down control in f3 the value to be changed (passed) to fom2 f2 ; How Can i do this ; Thanks