The theme does not support sidebar on a page/post basis. You can try using one of the plugins which help do that. Here are a few –
http://wordpress.org/extend/plugins/unique-page-sidebars/
and
http://wordpress.org/extend/plugins/sidebar-generator/
The second one looks promising since it supports sidebars for posts too but needs small fix. Pls see the forum for the plugin here –
http://wordpress.org/support/topic/plugin-sidebar-generator-fix-for-wordpress-34
I hope I understood your requirement right. If not, let me know.