How can I make my navigation bar fixed but on specific sections on my webpage?

My digital portfolio is going to consist of “4 sections” which is 4 separate scrollable web pages together. Please note my sections are also referred to as parts. For example, section one is #part1 and this goes all the way up to 4.

On #part1 I don’t want the navigation bar to be visible. However, on section 2,3,4 which is known as #part2, #part3, and #part4 I want the navigation to appear.

Here is an example site that I found which is how I’m aiming for my portfolio to look like in terms of the navigation bar.


How can I place my navigation bar on section 2,3,4 but not be visible on section 1?

My site code

I got recommended to use this. However, I wasn’t sure how to implement it.

Answered a similiar question not too long ago here -