No, what you heard was rubbish.
Just follow the on-screen instructions in Acronis. I recommend doing a Full Backup of C:
Your back-up will appear on the external drive in the form of an icon - hover over that icon and you will be presented with the date and size of the backup file.
I would advise you NOT to bother with Incremental or Differential backups, IMHO they are a waste of time, unless one is making lots of changes on a more or less daily basis.
Having made your backup, don't forget to run the Validation as well.
I make full backups on a Fortnightly basis, because I don't make many changes in the meantime.