Piece of cake Fred.
What you've ended up doing is slicing/saving your Ps document's background colour as part of the images that make up your site's look. Generally that's not done, but it's an easy fix.
Not that it matters much to you now, but the option in Ps's '"Save For Web" options window to "save a copy of the background colour/layer" might or might not help you, depending on what you're trying to achieve.
None-the-less... your solution now is a simple one. Put this code within the <body> tag in all of your html pages (it's near the top of the code): bgcolor="#put your color number here". For example: bgcolor="#4e6b2a".
To get this specific hex number, simply use the Eye Dropper tool and click on the background colour in your Photoshop web page document. This will assign your foreground colour to the toolbar. Click on that colour in the toolbar and at the bottom middle-right of the colour editor window that opens you'll see the hex code for that colour. (See the sample image attached) Copy&Paste that hex code to your html page's BODY tag the way i explained.
Just open your html document with Note Pad (or the Mac equivalent). The <BODY> tag is easy to find.
Hope this helps.
