Menu
Go to Admin -> Appearance -> Menus.
Sarsa has one menu with a display location and several menus that you attach to widgets. All of them are managed on the same screen.

To change a menu, click Edit on its row. Add pages, categories, tags or custom links from the boxes on the left, drag the items to reorder them or to nest them as submenus, then save.
Main menu
The main navigation of the header. The display location is Main Navigation (tab Menu settings at the bottom of the menu editor). The demo menu has Home with the 8 home layouts as submenus, then Lifestyle, Travel, Post type and NFT.

Go to Admin -> Appearance -> Menus and edit "Main menu".

TIP
A link can carry ?header=type-N (for example /homepage-interior?header=type-3) to show that page with another header style. The demo menu uses this to preview the header styles. See Header.
Top bar menu
The small menu in the dark top bar, next to the language switcher and the social icons. The display location is Top bar menu.
The top bar is part of Header style 4 and Header style 5 only. Choose one of them in Theme options -> General -> Header style to see it.

Go to Admin -> Appearance -> Menus and edit "Top bar menu".

Footer menus
The columns at the top of the footer are Custom Menu widgets. Each widget shows one menu: Footer-Worldwide, Footer-Politics, Footer-Entertainment, Footer-Business, Footer-Health and Footer-Trending In. The small links at the very bottom are the Quick links menu, shown by the Copyright footer Menu widget.

Go to Admin -> Appearance -> Menus and edit the menu, for example "Footer-Worldwide".

To change which menu a column shows, or its title, open Admin -> Appearance -> Widgets. See Footer.
Menus in another language
Each menu can be translated. Open the menu and use the Languages box on the right to switch to the other language. See Translate.