Header alignment with site body

I am having some difficulty with centering the header image with my website. The header image is aligned to the far left with the body centered nicely on the pages below.

I would like to accomplish the following:

1) eliminate the repeating image so that the header only displays a single instance of the image (no tiling off to the right of the screen.)

2) Align the header image with the contents of the website below (the default is far left justified)

(I cannot post the website url at this time but I hope that the issue is relatively easy to convey: how can I align the header image with the content below and eliminate the tiling of the header image.)