The TinyMCE Rich text editor is not your friend, really.
For those who don’t know what I’m talking about, TinyMCE is one of the editor style options available to you in your CMS editor. This option is attractive to most novice users, as it produces something like a WYSIWYG (what you see is what you get) editor. In other words, it attempts to approximate what you’ll actually see on the web page when you edit the code.
At first glance it looks pretty good, but it produces code that looks atrocious and can behave in unexpected ways. Your best bet is to use the EditArea code editor and learn some basic html. The results will be pages that behave more predictably, are styled more consistently, and are more editor and SEO friendly.
If you know no HTML at all fear not, it really isn’t as hard as it looks, and is much easier than any other ‘programming’ language. You really only need to know the basics to get started – as you get more advanced you’ll be able to supplement your knowledge a bit at a time.