How do you download operation system

[AC Question]

new phone to me but was told I had to download an operation system

 

[Tim1954]

Hmmm what kind of phone? If you go to settings>about device>software updates..check for updates.. (wifi is good, some updates come in over a gig!)
That will check if you need to update.. if there's update available it will prompt you to update. Follow prompts. good luck