When you have just activated the theme, a main menu is automatically generated by WordPress (“fallback menu”).
You probably want to change it to your own custom menu structure. Here is how:
- From your WordPress admin panel, go to Appearance > Menu.
- If you haven’t set any custom menu yet, you will see a “create a new menu” link. Click it to create a new menu and give it a name, such as “My menu”.
- From the left column, pick the items you want to add to your menu. They will appear in the menu on the right.
- You can organize the menu items on the right side with a simple drag-and-drop.
- Once you are done organizing your custom menu, click “save menu”.
- In the “Manage Locations” tab, you will see one or two dropdown lists depending on the theme you are using.
- Pick your new custom menu from the corresponding dropdown (Main menu or footer menu) and click “Save”.
- Your new menu is now set !
Extensive documentation about the WordPress menu system can be found in the official WordPress codex: Menus Screen