Upgrade jelly bean to lollipop

[AC Question]

Hey guys, I just got my father's old phone, it's a Galaxy S3 (I know, it's old). I want to upgrade it to the Lollipop version, right now I'm using Jelly Bean 4.3 and I can't update it, so I decided to just upgrade whole my phone. Can someone help me ?

 

[belodion]

Go to Settings, About Phone, Software Updates, and see whether there are any available.
I doubt that the S3 could run Lollipop, however.