Hey @abhi00123,
To do that you have to add Sticky Menu (or Anything!) on Scroll plugin and after that follow the steps.
open the Screen Shot.
1. Open the Sticky Menu (or Anything!) on Scroll plugin from settings.
2. Add #header in sticky element which means which section you want to stick.
This plugin sticks the header section on scrolling.
Or You can also do that using some css code.
#header {
position: fixed;
left: 0px;
top: 0px;
width: 1840px;
margin-left: 0px;
padding: 0px 0px 15px;
margin-top: 32px;
z-index: 1;
background: rgb(255, 255, 255);
}
.main {
z-index: 0;
}
Add above css code into Appearance → Customize → Additional CSS.