I cannot read text in my WYSIWYG editor!?!

You cannot read the article text in your WYSIWYG-editor because it has some annoying black/blue/some other dark colour?
Is that colour the same as your site template's background?

Well, it probably IS your site template's background that makes reading impossible in your editor...

To solve:

edit one of the editor's CSS files. Look for editor_content.css or editor.css
or put the following CSS code at the end of your template's CSS file: template_css.css

.mceContentBody {
text-align: left;
background: #FFF none;
font: normal 11px Arial, Helvetica, sans-serif;
}