Welcome to AFF
@Vivp .
Assuming you want to redeem Qantas frequent flyer points for your flights then first step will be to transfer your Westpac points to Qantas frequent flyer.
You’ll need a Qantas frequent flyer account so if you don’t have one, open that first. Now I don’t have Westpac so I don’t know their exact procedures
but on their points section there’ll be a redeem area and you should be able to select your Qantas account to redeem or transfer them to. It probably won’t be one for one. You’ll probably get fewer Qantas points for your Westpac. EDIT: see below - you can' transfer direct from Westpac to Qantas Frequent Flyer
Don’t transfer them until you know how many Qantas points you need and that there are flights you can get.
Now the redeeming part on Qantas is more complicated and I won’t be able to explain here. Your best to have a look around this site.
If you’re after an upgrade, then you book your regular flight making sure that it’s in an upgradable class of fare and then apply by the website for an upgrade. Depending on your status and the popularity of the route and how early you book will determine if you might get the upgrade or not.
if you meant to say a purely points flight rather than an upgrade of a paid flight then the process is different, but I won’t go into that if that’s not what you mean.
But your best bet is to have a look around this site (including along the top where there are some good articles ) to get a better idea and then come back with some more focused questions. You might want to have a look at the Westpac forum on this site to get you started.
PS Westpac may allow you to transfer your Westpac points to other airline frequent flyers schemes. Have a look to see if they do and maybe those schemes will give you better flights and availabilities rather than Qantas. Qantas can be very difficult to get out of Australia on. Singapore airlines (Krisflyer) for instance is much easier to get a points flight out of Australia especially if you book a long way ahead.
Flights redeemed for points won’t be free however - there will probably be hundreds of dollars in taxes and carrier charges for a long haul flight.