In order to upload Joomla files, you will need an FTP software. I use and also suggest you to use free ftp software FileZilla. Click here to download FileZilla and install it.
Open FileZilla and type your Ftp adress, username, password and clik the connect button. Upload Joomla files into public_html folder. This folder name can be different in different hosting packages.
The video below shows how to upload files into web hosting package by using ftp software.