** to swutch between class in storyboard with the code

Hi

please help me get it working.

im using xcode 4 and i want to swith from main view to second or third view with a class
based on user input

main view have a textbox and a button
if user insert 2 and press a button he goas to secondview controller class
if user insert 2 and press a button he goas to thirdview controller class

i added the if statement but how to call the second or third view by the code

Thanks A lot