Sidebar img / colours

I have changed the colour scheme of my website from the grey/black/white/blue template in Retina theme:
https://innersenseyoga.com.au/

I cannot seem to change the grey-to-white blend background colours in the sidebar.
It seems the sidebar background could be an image:

#sidebar {
padding: 40px 0 40px 40px;
background: url(images/sidebar-bg.png) repeat-y;
}

Where is the image? How can I change the grey to ffe9b0 to match my colour scheme?
Thanks very much!