Updating members details

Is there a way that members who have subscribed to be able to update their information on the system? For example, if a member has changed his email address can one create a page which will allow him to do so? This seems so obvious, I am reluctant to ask the question, but I can't find an answer on the documentation.

Yes - just put a menu item in that points to the OS Membership User Profile

Great and many thanks.
It works well, except I would like to change the order of the fields on the page. Is there a way I can do that?

Yip - go to custom fields in the component and drag the fields to the order you want them in as you would for other Joomla lists of objects that you want to re-order.
Done.