To upload files to your server, go to File Manager in your cPanel account.
The server root folder is located here. If you want to upload files to a subfolder, use the left-hand folder tree.
Public_html is a root folder for your website Wordpress files. Here you can find the detailed guide to Wordpress file and directory structure.
Use the Upload button to upload files to your server.
Once the file has been uploaded, you can unzip it by pressing Extract.