How to use Layout Options.
1. Go to Dashboard > Theme Options > Layout
2. Here You have Layout related Options to customize your Site.
3. Select your Site Layout from the DropDown Value. ( Values are Wide, Boxed, Fluid )
4. Set your Site Background Image and Background Sizes, Position, attachments, Etc...
5. You can also select Main Content and Sidebar Content Alignment By selecting the images.
6. Click Save Changes Once you're done with settings.