Here's a quick tutorial on how to change the background color of your installation of Market to more match your website's "vibe".

First, open up the stylesheet file "style.css" in your theme design editor.  Near the top, you'll see the BODY attributes.

Somewhere within the braces, you'll want to enter the following:

background: silver;

For novice users, replace "silver" with any named color (named colors include: aqua, black, blue, fuschia, gray, green, lime, maroon, navy, olive, purple, red, silver, teal, white, yellow)

Mke sure you don't forget the semi-colon at the end.

Save the file and refresh your website page to see the changes.

For more advanced users who know the hexidecimal code of the color you desire, you can enter the hex code with pound sign (#) instead.  Similar to:

background: #C9D6C9;

You also have the ability to set a background image as well if you desire.  You can read up on how to format it here on this page:

http://www.w3.org/TR/CSS21/colors.html

For changing the background, there are 2 things to work with. 

If you go into your "custom-styles" folder, you'll see all the custom stylesheets available.  Find the one that you're using ("sugarandspice" in this case), and inside that folder you'll need to edit two things.

(sometimes it's only 1 thing you need to edit, but this particular style has a compound background.  (2 parts)

The two things you'll edit are:

1.  The header background image named "header_bg.jpg".  You'll use a graphics program to edit this image file, and then re-upload.

2.  The background color value listed in the "body" element.  (By default it's on line #14.)  Just change the HEX number code to whatever you want, and save.

Under the Market Theme menu area, click on "Settings". On that page you'll find a place to upload a logo.

That section also has a lot of other options as well you can modify.