Resizing the radiate theme

Hi,

I have looked through the forums for a good answer to this but to no avail. The site I am working on is edenscapes.esy.es.

I have started trying to changing the width of the but am finding it tricky. It looks to me like the line the main navigation is on starts on the far left although I have managed to bring the right side in. I now want to make the text and widget areas start and finish in line with the header image.

Also, I want to change the white space to the left and right side of the header image but can not seem to find it in the style sheet. Any advice would be appreciated, I am a relative newbie to CSS, originally I made my changes to the stylesheet itself only to have recently lost my changes after an update! I am now using a custom CSS plugin and will probably disable auto updates today also.

Thanks in advance.