You can upload your files directly via the File Manager. You can find it in your control panel area.
There’ s usually a upload limit through File Manager. So if you need to upload a large file, you should use FTP client. FileZilla (it’s free) and SmartFTP are two popular FTP softwares. Your FTP details can be found on your control panel (e.g. on the View FTP Details section).
Be aware that All files must be uploaded to the Root directory (e.g. public_html folder for cPanel hosting). You may create other sub-directories inside root directory if needed.
There must be a file named index.html or index.php (default.html, default.php, etc.) inside the root directory for site to be working properly.