Hard to say ...
If you have been designing/building websites for a long time, and you have a bunch of previous satisfied customers, you can get away with charging a LOT more then someone who hasn't done any professional web design before.
If you are an experienced veteran, chances are you wouldn't post that here ...
So I'm going to go out on a limb and say that you probably have dabbled in webpages before, perhaps a homepage, and/or helping friends set up their home pages ... If that's true ... it depends on your skills and what the site entails. If it's just html with no DB, no PHP, no Javascript, etc ... nothing too fancy .. .then maybe $10 to $15 per hour for the first job, and if the customer is satisfied with the quality and timliness of your work ... in the future ...charge more maybe something like $20-$25 per hour, if not, work on your skills a bit .. and try again later.
If it's a site that requires extensive knowledge of SQL, PHP, html, maybe some Javascript and maybe some Perlscript ... then your services are more valuable and you can charge more ... maybe $20 per hour to start, and if they are satisfied charge a bit more for future buisness say ... $25 to $30 per hour ....
Again ... it's all about experience ..... if you don't have anything to show for your skills, your skills aren't worth as much the guy who has the experience, even if you do better work .....