Redirecting to a particular page

I am currently working on a web project where if the user wants to enroll for a particular program the user clicks on enroll and they are redirected to the log in page. but I want that they should be automatically redirected to their profile pages if they are already logged in.What should I do.Also I am a newbie to stackoverflow so I don't know how to present my code here.If someone would tell me how to do so I am totally open to do it.