If you want to display your submenu, please make sure that your page uses a layout with more than 1 column (i.e. 2 columns or more):
Login to your inCMS website. In the left column select the page which is supposed to contain the submenu. Click on “edit page” in the tool bar in the left column (symbol with pen and white page). This opens a new tab (properties). Go to the section "Layout" and select a layout including a sidebar (2 col, 2 col right, 3 col). Click on "save and close".
Also, make sure that all your subpages use a layout with more than 1 column.