In case you want Virgin Australia business class upgrade, here are the quick steps you can follow: 

Go to the Virgin Australia website online
In the Book section, click on 'upgrade options' under 'Manage Booking'
Now login by clicking on 'manage your booking' on a new page 
Provide the booking reference number and last name, and click 'manage booking.'
Select the ticket you want to upgrade and choose the upgrade options 
Select the class you wish to upgrade to and pay for the fare difference 
Follow the prompts, and once the upgrades are complete, you will get a confirmation 

How much is it to upgrade to business on Virgin?

The amount needed to upgrade to business class on Virgin depends on several factors, such as the class you want to upgrade to, the Upgrade option you are choosing, your elite status level, etc. In case you opt for Bid an upgrade, the amount is what you want to pay. If you decide to upgrade using the velocity points, it also depends on various factors. However, if you still want to know the upgrade cost, do a demo upgrade, and you can check the price on the payment page. You can also talk to Virgin Australia customer service and ask them about the upgrade cost in your case. 

How do you get a free business class upgrade for  Virgin Australia?

You get four complimentary upgrades per year if you are a Velocity Platinum member. You can upgrade from Flex to business class seats for free using Velocity points. Moreover, another way to get a free upgrade is to contact the airline and ask them questions. You can also reach the airport on time and ask the Virgin Australia team to consider you if free last-minute upgrades are available.