After install and activate the NicheBase theme, you’ll need to set up header areas like logo and main menu.
Custom Logo :
The theme displays site title and tagline by default, as shown on the demo. You can also display a custom logo, and optionally hide the site title and tagline.
To upload custom logo please go to Appearance > Customize > Site Identity. Here you can upload your custom logo in Logo, Site Title and Tagline and also upload Site Icon that will shown in browser tabs and bookmarks.
Main Menu :
After setting up custom logo options in menu. need to set up main menu for your site.
To set up menu in your theme please go to Appearance > Menus.
Here You can get list of Pages, Posts, Custom Links, Categories you can choose your menus by select that page and click add to menu.
After adding menu you can change the menu name in Menu Structure > Menu Name also save your menu by clicking Save Menu button.
All themes displays menu by default if you select Display Location > Main Navigation checkbox. Also click Save Menu once again.
You can add number of Pages and Posts in menu after creating those in your dashboard.
To know more about working with Menu please read the following articles: