You want to add something a user can order and then you get an email? Here are the basic steps:
Install a module, or use the none module. If using the Universal Module, create Universal Module Product. If you want to ask the customer for something during checkout, like their domain, then enter a service field for that. You cannot charge extra for service field options
Create a Package using the module, and add it to a Package Group
Install payment gateways you want to use (Settings > Company > Payment Gateways)
Create an Order form, and assign your package groups to it, and select your gateways and currency. Packages > Order Forms
Under Billing > Overview, click the cog/gear icon in the Orders widget, here you may subscribe to get order notification emails.