By "skin.ascx" I meant whatever your page skin's .ascx file is named.  The file name varies from skin to skin.  Skin files for pages (as opposed to containers) should have body tags in them, as a html document is not valid unless it contains one and only one body tag. 

If you don't have a body tag, then either your html is invalid, or there's something else going on with your code that you haven't revealed.  In ASP.NET it's possible to set up a .Master page which acts like a template, and any page based off of the .Master inherits the contents of the .Master page.  If you're using a .Master page in your skin package, that's probably where your body tag is.  To date, I have not seen any skin packages that use .Master pages, but my experience with DNN skinning is fairly limited.

Are you looking at the *page* .ascx file for your skin, or the *container* .ascx file for your skin?  I'm talking about the body tag in the page skin file.  It would be located in this dir:

\Portals\_default\Skins\[myskinpackage]\

and not

\Portals\_default\Containers\[myskinpackage]\

All of *my* page skins have an HTML and BODY element in them.  This seems to be standard/defaut for the skin packages for dnn framework that I have used.

At any rate, it appears that your real problem (the background color) is solved by this solution, from another thread:

this is caused by a black color specified for the html body tag in your skin. you can disable dynamic application of css in extended editor settings (beneath the editor) and select static in section Editor Area css. save your settings for the whole portal.

Hope this helps!

--Chris