Heya all at Webdeveloper.com!

I'm in need of some help I think. In our class in school everyone is supposed to pick a project and work with it for 1 year. Me and a friend wants to create a company (it's called a youth company and is not deadly serious, yet all the basic s of a real company you must learn).
Anyhow, since we are both interested in webdesign we want to create a local webdesign company which creates simple websites for private persons or smaller companies. We will only use html&css (as of now) The one thing im worried about is, how are we going to deal with customers who wants to update their site by themselves? Maybe it's a guy who's not into this html-thingy yet he wants to be able to publish news/add images etc. on his own. Then I can't really send him the website map, can I? I mean won't it be too difficult for him? So I'm wondering if it's possible to use some GUI-program to make it easier for customers to update their websites? Are you aware of any programs like that? And I have no knowledge in php/Sql what so ever (though I will begin to study it on my own anytime soon).
Do you know anyone else with similar problems, how did they solve it? Should we just ignore our idea about a webdesign company? We aren't very skilled but we think its very fun to create websites
Hope you're able to reply after this wall of text.

Great thanks in advance!