You can manage main menu by going to Appearance > Menu
Type menu’s name
Click Create Menu. You can generate menu item from left side and drag the generated menu at the right side to sort it. After that you can assign menu to theme location.
How to configure Mega Menu
Select the menu item you want to make as mega menu and activate the mega menu option
The first item after the megamenu item will be recognized as mega menu columns the other items under it will be normal menu items.
Add icon for menu
Theme profiler supports awesome font. To establish icon for menu, you can do with below guide
Step 1: You click font awesome Icon will display icon to select
Step 2: You select 1 icon after that you can copy class
Step 3: Next you can paste into Title Attribute