updating a MacBook Pro (Retina, 13-inch, Early 2015)

Hi, could you please help me with the following:

I need to upgrade my Mac, when i press on software update it says has no updates. Need to install some software for uni and says the application requires OS X 10.13.6 or later.

Not sure which update is the best option for MacBook Pro (Retina, 13-inch, Early 2015), the current version is OS X El Capitan 10.11.6?

Thank you!