Hi there and welcome
Can you click on the apple logo, then click on the "About This Mac"
Tell me the OSX version please.
You need to update the Mac to El Capitan which includes the Safari update, this is how it works.
First, backup your data as you should so with any updates
Then go to the upgrade page on this link
CLICK ME TO OPEN
Click the download button and follow the onscreen instructions to begin your upgrade.
Once done, Safari is then updated to the latest version
If you have any problems, or would like any additional information or assistance, please do not hesitate to let me know.
And if you can take a second to rate my service by clicking one of the stars at the top of the screen then submit, that would be greatly appreciated.