Color in plain text documents

I have some documents that are plan text. They have white text on a red background. If I convert them to rich text the color goes away. Somehow I was fooling around with highlighting and have created this mess.  How do I get back to black text on a white background.  AND, can I highlight just a few words or lines in a document? :-[

Allan,

highlighting is only possible in rich text documents. To change the colors of plain text, just select the contents of a plain text, select all and open the color panel. Afterwards just choose the desired background and foreground colors (these attributes are persistent and identical for all plain texts).