Need help with mark as paid custom event

Hello, I need help regarding klaviyo custom event. I have a store on Shopify and use Klaviyo for my email marketing needs. Currently, I am facing an issue where I need to send an email to customers whenever an order is marked as paid on Shopify. Unfortunately, there doesn't seem to be an existing event for this activity in Klaviyo.

Could you please provide guidance or support on how to create a custom API event in Klaviyo for when an order is marked as paid in Shopify? Any detailed instructions, documentation, or examples would be highly appreciated.

Thank you for your assistance and looking forward to your response.