I can't add gmail account to imac or iphone

Just bought a new iPhone 4s and I am having trouble adding a gmail account to it or my imac. I just created a new gmail account and I can access it through my browser but when I try to add to iphone or Mail on my imac it says the user name or password for "imap.gmail.com" is incorrect. I know I am typing correct user name and password as I can log on through my browser. Any thoughts?