Newbie Help, please - Navigation Bar

I'm trying to change the background color to just a plain black. Seems simple almost too simple, but nothing I've tried is working. I'm using the "prometheus" navigation bar and "matched" it to my site (the grid site). I want the orange to pop up with mouse over, but I just want the background a plain simple black to "blend in" to the top, so basically all you see are the words, not the buttons.

The pictures are as follows:
1) shows the prometheus nav bar that I'm trying to get all black background
2) shows what I want it to look like
3) shows why I want the prometheus - because I like and want to keep the orange pop up with mouse over.

Thanks for your help!

Welcome to TalkGraphics

In the Page & Layer Gallery, click the S next to the Mouse Off Layer to isolate just this layer.

Select the Fill Tool, then hold down the Ctrl key and click the rectangle behind the first button (Home). This selects just the rectangle and not the text which is grouped to the rectangle.

From the drop down list at the top of the screen, select Flat. Edit the color if necessary to march the background color. (Drag the eye dropper tool from the bottom left of the screen over the background color)

In the Page & Layer Gallery, click the S icon again to turn off the isolated view.

This is how I'd go about it:

WOW! Thank you Both so very much!!! That is exactly what I wanted to do. It worked and I'm ready to dig in now, the site may just get some additional changes now that I know more! Thank you, thank you, thank you!

Egg Bramhill, (in addition to the thank you so much) thanks for the video. I learned how to go about other issues I was having as well, but didn't know how to go about asking. Very detailed! Thank you!