Creating and editing an account

Why do I need to make an account? How do I make an account? Which details are required and why? How do I edit my profile? How do I change my profile photo? How do I change my email address? How do I change my password? Why would I connect my account to Facebook? Why would I connect my account to Google? How can I add a campervan to my favourites? How old do I need to be to make an account?