Graphics

I am still working on graphics for menu. Now I actually put some codes. But there are three dreadful problems. First one is that I cannot create ui file. I tried to create ui component inside the asset file, but instead of file, new scrip was created, so I deleted. The second problems is that I cannot input the .pack file. I am watching the Youtube video how to create menu icons.https://www.youtube.com/watch?v=WO52F0M_tio
It is definitely helpful, but because the codes we have and the codes he has are different. So it is hard to compare them and put translate his code to the compatible codes for our program.
The last problems are even though I read through instruction or information, I could not fully understood the difference between atlas and table.
So far I made little progress, but I start getting some concept. This is my code so far, it does not work yet.