Asp。Net mvc，如何进行异步和等待方法。

I use this two actions to send email to admins about inventory status when it's time to make an order... But When I call SendEmailToAdminUser .. it takes time and side by side I cant work with other functions... waiting litle long.. I want to change those functions to async and await Task ... but I don't how to do. I tried to change from JsonResult to ActionResult ...I use this two actions to send email to admins