Also, what version is yours? Seeing this go back and forth is painful, so googled it.
1) Open the Editor and typed in some text
2) Clicked the Prefs button in the main session window toolbar, clicked on Styles
3) Click on the General->Text Editor style.
4) Changed the Background Color to Gold
5) Back in the Editor window, the background is now Gold
6) In the Editor window, I did a File/Save As
7) In the Save File dialog box, I select "HTML files" from the "Save as Type" selection. Then entered a filename of "test.htm" and clicked OK.
Opened the test.htm file in Firefox, and the background was Gold, just like it should be.
.
EDIT: lol, forgot step eight written like it was is an emoticon.