How to create a web site in Sharepoint using C#

Hi there,

Well, I'm a newbie for this point, and now i need to create a web site in sharepoint using c#, and I like to know if someone can tell me what object/class could I use to make reference to the environment of Sharepoint, I mean something to create a instance of object to change its appearance.

Could anyone give me a hand please.

Thank you.