On the left pane, under Appearance choose Menus
In Theme Locations (center column) Top Menu (the primary navigation) must be selected for the horizontal menu to appear.
Under Pages (in middle column), click the View All tab.
Find the page you created and check the box next to it.
Gray horizontal bars will appear in the right column – the menu area – with your page name.
To reposition, left click on page name (horizontal bar) and drag and drop it where you want. Notice the dotted line as you drag near the appropriate place to “drop” the bar.
To make nested, or child links, left click the horizontal bar, drag to the right to indent it – a dotted line guide will appear.
Note: where you put the bar/file is where it will show up on the top menu bar