If you want to know ALL about web hosting, domain names, etc, I think taking a class in this area would be the most beneficial to you, since we can't possibly cover everything in one conversaton.
But anyway, a good place to start...
Glossary of Web Hosting Terminology
How to choose a good domain name
And about the semi-professional design... well, it depends on how much experience you have but one easy thing to remember: keep it simple! Pick two/three colors, decide on a basic layout, and from there on keep it simple and consistent.
Here is a website I designed for the business department of a school... it's a very simple website, and they have changed minor things over the last three 3 years, but the main design is still intact.... why? Because it's so simple. http://parkwaysouth.net/
If you have any more specific questions, feel free to come back!
Hope this helps.
i want to make a website for my student organisation but i want to make it look semi-professional. so i want to know about all the terms associated with web hosting and things like Domain Names etc etc.