Open Iglubox from the notification area and go to Backups (the app also asks once, right after setup). Tick Desktop, Documents or Pictures, or click Add a folder… for any other folder or an external drive. Iglubox keeps a copy in your account in Computer backups → <your computer>; it is not synced to your other computers.
By default new and changed files are backed up as soon as they are saved. Under Schedule and options you can back up every few hours, once a day at a time you choose, or only when you click Back up now. Every change is a new version of the file, and files you delete on the computer go to Deleted files, where you can still recover them (or switch on Keep files I delete from this folder). If many files disappear at once, Iglubox asks before removing them from the backup.
To get files back, click Restore… on the folder: back into the same folder or into another one. Nothing is deleted; files that would be replaced are kept next to the restored ones. Older versions of a single file are restored on the web from its Version history.