If you are not happy with the background color of your blog, you can very easily change it in New Blogger. In the Dashboard, for the relevant blog, click LAYOUT (if in other pages of your Blogger account, you may have to click the TEMLPLATE or PAGE ELEMENTS tabs instead) and then click on the "Fonts and colors" sub-tab. You will be presented with various choices of what you want to change (Page background color, text color, etc, and also you can pick the colors you want by clicking on the "color box" or entering the color hex code:
You can chose from colors already present in your blog (first section), colors that can blend with colors of your blog, or "more color". If you are fussy, you can even get a wider variety of colors by entering the color hex code. For this, ColorPic is a great tool. If you want ColorPic (free) type or copy-paste "colorpic" into the search box above, tick the "Web" radio button and search. Their site should appear in the first result. If you want more information, see Blending colors of your ads with the colors of your site. There is a screenshot that will help you use the tool.
And if you are hesitant to tinker with the color, I think you should not be too worried because there is a provision for you to revert to the template default color. You should see a link on the right in the screenshot that says "Revert to template default". Click on that link (not in the screenshot but in your Blogger page) and everything should be back to its original state. Please note that I have no occassion to do that, so I am assuming that that is reliable. In anycase, you should have back uped your template as shown in the post Backing up and changing New Blogger template (click BACK to get back to this page).
If you only want to change the background color of the main column, sidebar, etc, refer to Chang background color or image of main column (posts).