What is the base url in your Settings? That's what determins the "fixed" part of the url of your content items (pages). When you edit your page, on the top there is a field "permalink" right under "title". There you can put
in the url you'd like (trailing the "fixed" base-url mentioned above).
I'm guessing in your case the base url would be "http://www.domain.com/
". So you just add "About" in the permalink field.
(This does presupposed a correctly configured webspace/webserver of course)