In Pixel Together, you can create a fixed header/floating navigation that remains at the top of your page, even as you scroll down the page. Note that you can only select this option for your first section on your page.
In order to do this, click on the drop down menu on the top right corner of your section and select section properties. This will then give you the option of three types of section types. Click the ‘Fixed Header’ box and ‘Apply’ to confirm changes.