When you launch iBackup Extractor, you will be presented with a list of existing device backups which have been detected on your computer. To access a backup, select it from the list, and hit "Explore" (Windows) or "Browse Selected Backup" (Mac).
iBackup Extractor can access backups created by iTunes (or Finder if you are using macOS Catalina or higher). It cannot, however, access backups stored in iCloud.
If an existing backup has not been detected in the default location, you can tell iBackup Extractor to look in a different location on your computer by using the "Change Backup Directory..." (PC) or "Change Location" (Mac) button.
If your iPhone backup was encrypted when you created it, you will need to enter your backup encryption password in iBackup Extractor to view the contents of the backup. iBackup Extractor uses this password locally and securely on your computer for this purpose so that you can open your iOS device backup - this password is not saved or shared.
After this is done, you can start browsing through your backed-up data and extract it to your PC/Mac. Using the feature selection menu on the left of the program, you can browse through your Calendars, Contacts, Notes, Messages, Photos, Call Logs and more, and extract these files to your computer.