To change the background color behind your text (or your text color), you can use this code (often used on forums to hide "spoiler" information for movies or TV shows; substitute 'black' with other colors):

<font class="small">Code:</font><hr /><pre>
&lt;FONT style="BACKGROUND-COLOR: black"&gt;&lt;FONT STYLE="color: yellow"&gt;
This is some text that you won't be able to read if it were black on black.
&lt;/font&gt;&lt;/font&gt;
</pre><hr />

<FONT style="BACKGROUND-COLOR: black"><FONT STYLE="color: yellow">
This is some text that you won't be able to read if it were black on black.
</font></font>