Here are some things that will help you get your CSS question answered more promptly and easily.
0. Please don't ask us to teach you CSS if you don't know it at all. There are better places for that kind of thing. http://www.google.com/search?q=css+tutorial
1. Provide direct links to the stylesheets in use, and possibly a page where the problem is happening. It's a pain to have to view source to figure out what skin you're using, then manually type out a big url to see the stylesheet.
2. If a problem only exists in some particular browser or OS or screen resolution, or if you have to click something to get something to change wrongly, please say so. It'll prevent a few frustrating replies that say, "Seems fine to me."
3. If you know a little about what's breaking, like the XHTML classes/ids/elements involved in the malfeasance, please don't be shy. It'll help you get your question answered more quickly.
4. Search is your friend. Use it.
5. Validate your code before posting here. That might tell you what the problem is. (Every skin has little XHTML and CSS links at the bottom for validation. Of course, the page must be online to do that.)
In other words,
Please don't make us guess what you mean by "that thingie at the top of some of my pages that happens sometimes and looks funny."
When you make it easy for others to help you, they usually do!