so far.....i have found DNN extremely un-intuitive. some basic questions:

i would think that most users of DNN would start by putting their logo in the logo area. so wouldn't the logical next step be to set the background of the logo area to match the background of the logo? but surprise surprise......this can not be done via the admin interface. even though there is an are specifically for the stylesheet....this one important item is not included. is it true that the only way to do this is to ftp the stylesheet and find the setting and change it and ftp it back? if so.....why?

how do you change the background color of the main content area? even though there is a setting in the stylesheet with the following comment and setting:

/* background color for the content part of the pages */
Body
{
    background-color: white;
    margin: 0px;
}

changing it does nothing. why???

(changing other settings on the same stylesheet does make changes)

what exactly does it mean when there are radio buttons which say ( ) site  ( ) host?

If you aren't already, I would suggest using Firebug for FIrefox to do your CSS development.  This will tell you exactly where you need to change your values.

In general, you put in new values into the skin.css file that goes with your skin.  You can overide most things (including background) in here.  Because DNN is a multi-portal solution, you shoudl be thinking about making changes at the portal and skin level, rather than at the DNN Core level. 

As for your logo : just use a transparent logo file (gif or png) and the background will come through correctly.

There is a bit of a learning curve when it comes to sknning, and it will never be as simple as a one-page .aspx page in a website.  That's because it is inherently flexible, and so each little piece is segmented to allow this flexibility.  If you just had one place to change the background, then you wouldn't be able to run 10 portals each with 5 pages with different backgrounds all on the one DNN install.

If there is a body background defined in the skin you can overrule that with the site settings stylessheet (portal.css)

But you should use the correct CSS:

body
{
background:#F00 none;
}

Because the default skin has a background-image, changing only the backround-color does not help