Adding a user profile option that controls template outputs

[MrEyes]

I would like to add a checkbox option to the registered user profiles that will allow them to choose to display the site header banner.

Now I know how to add the new profile option through admin CP.

and I know how to edit the header template to include an if condition check around the header banner html.

What I do not know is what the condition is I am checking.

Could anybody point me in the right direction?