In filezilla, connect to it and on the right box, click public_html. Check if you have random files and folders or just one folder with everything inside. Maybe you just dragged the main folder itself? If you have just the Mysidia folder: Go to the left box and open the mysidia folder, select all of the files inside, right click them and choose upload (while inside public_html on the right box).

How do I select all the files inside?

The tutorial makes it seem like my url would be something with .10xhosting, so if I already have a url and hosting site, why would I need to make a .10x hosting url?

You don't need, you already have a site. x10hosting is another possible host where you could have made an account. The tutorial is for both x10hosting and 00webhost (which seems to be yours), that's why it mentions both.

To select all files inside, go inside the folder, click the first file and then scroll down and then click the last file while holding the shift key (left shift)

Well if you are struggling uploading the files or installing the script, you can send me a PM about your ftp info and I can do it for you when I have time tonight or tomorrow. Also provide your desired admin username/password if you do not want the first admin user to be wasted.