Add a Personal Package Archive (PPA)
Personal Package Archives (PPAs) are software repositories designed for Ubuntu users and are easier to install than other third-party repositories. PPAs are often used to distribute pre-release software so that it can be tested.
Only add software repositories from sources that you trust!
Third-party software repositories are not checked for security or reliability by Ubuntu members, and may contain software which is harmful to your computer.
Install a PPA
On the PPA's overview page, look for the heading Adding this PPA to your system. Make a note of the PPA's location, which should look similar to: ppa:mozillateam/firefox-next.
Open Software & Updates via the Activities search bar.
Switch to the Other Software tab.
Click Add and enter the PPA's location (as noted in step 1).
Click Add Source. Enter your password in the Authenticate window.
Close the Software & Updates window. App Center will then check your software sources for new software.