I'm guessing you mean a variation listing?
The basics are shown here, so you will probably be able to get through the process with this: https://sellercentre.ebay.com.au/ebay-for-business/multi-variation-listings
I can provide additional help if needed, but it might be a while for me to reply as I won't get a chance to look back in until maybe tomorrow (others are likely to be able to provide assistance in the meantime).
