Starting point for custom Themes [closed]

I think it’s useful to start with childthemes

You can “extend” the default theme (twentyeleven). While using child themes the learning curve is smaller and it’s not required to use all the files. Sure you can create a child theme from the Toolbox theme too.
If you’re able to modify the header and footer you got already 50% from your design. Be sure you need to know CSS or you get stuck while WP theming.
Maybe you can create a theme for a “Page” first.