I can't see anything in your ebay history that shows a completed listing for a computer so I can't look up the actual ad. I think they only show for a few weeks in the sold llists so maybe it is gone from view now.
But in any case, my advice would be if you are setting up to sell other things on ebay, go through the ad carefully and make it strictly Australian sales only. I think there's a section you can tick to exclude other regions.
By rights, that should block any overseas buyer from bidding.
If you do sell something and any buyer wants to change the address you post to, just say no, you can't do that. You need to send only to the address registered on their ebay/paypal.
Personally if i were you, I'd also start out with small sales, nothing too expensive, till you get the hang of how things work on ebay. I don't think most buyers are scammers but there are a few so for now, make it as safe for yourself as you can.
