I'm new to Linux. I'm running Ubuntu 18.04 LTS and I want to find additional open source free software packages available for installation. I tried to add other software sources to the Ubuntu Software applications but after a lengthy process of updating the available applications by downloading updates, the new software repositories don't show and I have the exact same packages available as I always had. I used a repository list generator website to find the URL for the repositories to add.
Obviously I'm doing something stupid? I don't think I yet fully understand how repositories work despite much reading about it. Is it like having multiple Windows Stores? Or multiple Android Google Plays???
Thanks in advance for any help at all which would be greatly appreciated.