The dual navigation bar are completely customisable from Design--Page Elements, locate the 'navigation' section, click the edit link and add your links in the new pop up window that opens.
You can place a banner ad in the header section. Now moving on the slider, go to Edit Html and look for this code -
<li><a href='#'><img src='#'/></a></li>
Replace the first '#' with your post link and the second '#' with your image url, save the changes. The theme has two sidebars on either side of the main column, the right column comes with the Popular Posts widget, sponsor ads, blog archive etc. While the left sidebar can be used for other blogger widgets.
The theme has two versions - Personal (withour slider and auto read more) and business (with slider and auto read more). You can download both from the link below
Download the Sonya Blogger Template