A fixed menu, called sticky bar is a type of navigation bar always pinned to the top or to the bottom of the page while scrolling your LP up or down.
How to make a fixed menu (sticky navigation bar)?
1. Click on the top/bottom section of your landing page and change its size. It should be adjusted to height of typical menu (use the slider at the section or change the value in the right side panel):
2. Next, click on the 'Pin' icon in the edit section, so you'll pin it to the top or to the bottom of the page. To unpin, click it again.
Depending on whether you have pinned the menu up or down, you can get the effect like in the examples below: