<p>Configure at <strong>Admin → Extensions → Template Manager → rt_gantry</strong>, then go to <strong>Layouts</strong> tab and set the varying Mainbody/Sidebar layout possibilities.</p>

<p>Here, you can change both the grid size of the <strong>Mainbody/Sidebar</strong> position, but also the location of the sidebars. You can place the sidebars at varying <strong>combinations</strong> to the left, right or both or the Mainbody.</p>