Do you understand everything mentioned above or do you still need help?
In short, one of the ways to arrange all that is:
inside the htdocs folder
create a folder images and upload the desired images inside (you name each image to something so you can recognize it)
create a folder audio and upload .aac files inside (name each according to your wish)
create a folder video and upload .mp4 files inside (name each according to your wish)
Note: it is better to use YouTube because the max file size on the hosting is 10MB, which is too small for videos of higher resolutions and duration.
Then you enter the correct paths in the HTML code from your website
example:
and of course correct many other errors that your HTML code contains
If that’s too much for you