silly question: how to upgrade to Hikashop 3.0.1?

-- url of the page with the problem -- : shop.smartgart.com
-- HikaShop version -- : 2.6.3
-- Joomla version -- : 3.7.0
-- PHP version -- : 5.5
-- Browser(s) name and version -- : Chrome latest

Hi, I am on Joomla 3.7.0 and HikaShop Business 2.6.3.
I click on > Components > HikaShop > Documentation > Update./About
> "Your version is 2.6.3, the latest stable version is 3.0.1. Please click here to download the latest version of Hikashop Business and install it"

I can then download the .tar.gz file, but (silly question) how do I actually install it on the web server?

Did it. - Back uploaded the .tar.gz, unzipped, then "installed" the update.
No tables getting being dropped I think ... but a style sheet issue that I need to look into.

... my fault - patching back my changes in media\com_hikashop\css\frontend_default.css tomorrow ..

The error was not in the style sheet but in my category and product definition:
I had set an excessively large width that did not effect in 2.6.3 but did in 3.0.1.
So panels were simply overlapping with a huge white border, and the last panels in the row or those with bigger images won for display.
I misperceived this to be a style issue - it was simply misconfigured from my end.