Hello,
There's two options. The first is to use ftp, the other is to use the filemanager in cPanel.
The filemanager can only do it file by file, but you can compress the folder on your computer and then upload and decompress.
Ftp can upload folders as they are.
To access ftp, you need a ftpclient, such as filezilla for instance. The details you need to enter to connect with ftp is:
Host: Your main domain
user name: Your cPanel user name
password: Your cPanel password
Port: 21