Pour aperol and sparkling wine into your glass at the same time so that both combine well. That way your aperol won't collect at the bottom of your glass.
Top up with some club soda to your liking.
Add ice cubes if you like.
Garnish with a slice of orange and serve with an olive cold.
Notes
Use sparkling wine such as Prosecco. If you don't have prosecco, substitute with white wine. Theoretically, you can use champagne too but this isn't commonly done because champagne is more bitter and way more expensive.
Top it with as much cold club soda as you like. I personally never add more than 1 shot.