Adding to A Sidebar Menu
Under “Appearance” select “Menu”.
Under the “Edit Menus” tab, use the pull-down to choose the menu that you wish to edit then click “Select”.
Under “Add Menu Items”, find the page you wish to add to the previously selected menu. (You can also add a Post or a Custom Link). Once the page or pages have their check box selected click “Add to Menu”.
The item(s) will be added to the bottom of the menu list on the right; you can click the down arrow selector to change the text and/or to move the item within the menu.
Click “Save Menu” at the bottom right and the change will be reflected wherever that menu is displayed.