Using the Editor
At left, you'll see in the Navigation Box, a link "Add Content". Clicking this brings up the editor.
When you save a page, in the options at bottom make sure "Provide a menu link" is checked. For your first page (or only if you choose), leave Parent Item as <Main menu>. For additional pages, have the Parent Item link back to your first introduction / overview page (or an appropriate sub page).
The option for Weight allows you to order pages; heaving weighted pages fall to the bottom.
Under Publishing Options, for your first (or only) page, please check " Promoted to front page "
Please make sure the pages are organized as described, under <Main menu>, then back to your overview page. If you don't, a member of the IT team may unilaterally reorganize your pages.
Some after the event, the IT team will move your pages to the archives.