Help me fix my website

Greetings, my name is Nikola, I am from Serbia. I am 21 years old, studying computer science....

An acquaintance of mine asked me to create for her an HTML website for her school project/homework. So I picked up HTML and started learning the basics and creating a simple, mini website.
The goal is to implement as many features like videos, animations, text, pictures, music and similar, as much as possible. I did, everything was simple until I encountered javascript. I've never been the coding type, I've used tutorials from W3Schools Online Web Tutorials and YouTube.

So here's my problem:
First I've tried to implement a custom cursor set downloaded from the internet for my website, it just didn't work out, nothing that I've read. So I've looked up a tutorial on YouTube, to create animated circles that follow the cursor using javascript. It worked, finally, but... When I scroll down the page, the circles stop following the mouse cursor precisely, instead they are above it and follow it. It doesn't look pretty. That's one problem, the second is, by implementing this I kinda broke the links "Home", "Pictures", "Videos" and "About", also before by clicking on a picture in the "Pictures" section it would open the picture in full size, now it doesn't work, same with videos, its as if something is blocking the cursor from clicking on the content that's available on the website. These don't work anymore. Third problem is, the website got disorganized a bit, as if uecessary space for scrolling vertically and horizontally got added.

I am using notepad as my text editor for coding, I know it's a bit silly but yeah... I am really eager to learn HTML more since its fun and I kind off see myself in it a bit since I enjoy creating content. I am going to add a few more things but first I waa fix these issues so that I can move on in peace.

Hopefully someone here has time to teach me and correct me, I am going to include a stable version of the site and the one with the cursor (WIP), for comparison of functionality reasons~
Small amount of code, small website.

Stable version (how it's supposed to work, animated cursor excluded): https://drive.google.com/open?id=1d6...KtplTjYip3tFjc
WIP version (animated cursor included): https://drive.google.com/file/d/1tth...xISuVdU2r/view

Thanks in advance to everyone and sorry!