The File Manager lets you upload, edit and organise your website files in the browser without an FTP program. Open it from the dashboard under System Info & Files → File Manager.
Your website files live in domains → your-domain → public_html. That public_html folder is your site's root: a file called index.html or index.php there is your home page, and a folder called blog there is reached at your-domain/blog. The folder-tree button at the bottom right opens a side panel showing the whole structure, including a Trash Bin for deleted files.
The toolbar across the top has New Folder, New File, Upload and Search. To upload, click Upload, pick the files (or drag them onto the window) and they land in the folder you are currently viewing. Large sites are quicker to upload as a single .zip file: upload the zip, tick it, and use Extract from the selection toolbar.
Tick one or more files and the greyed-out icons above the list become active: Rename, Copy, Move, Extract, Download, Compress, Edit, Permissions and Delete. Edit opens text files such as .html, .css, .php and .htaccess in a code editor; click Save when you are done. Deleted files go to the Trash Bin, from where you can restore them or empty it.
Permissions rarely need changing; the defaults of 755 for folders and 644 for files are right for almost every site. If a script asks you to make something writable, use Permissions and tick the write box for the owner only.
If you have any trouble, raise a ticket and we will sort it out.