I don't think there are any courses available especially to manage an Ecommerce site, however you can always brief yourself with vital activities involved ecommerce operations. I assume the obvious, you plan to start your own Ecommerce site (Potential Industry). But it's important to understand the intensity of work it requires, it involves several backhand & front-end activities right from Procuring/Manufacturing - Storing/Warehousing - Logistics/Delivery to Advertising - Customer Support, etc. Managing all these without proper resources & man power that too at once it next to impossible.
It depends upon what platform you're planning to use and what your purpose for building an Ecommerce site is. Are you a business owner looking to build your own site or are you a web developer looking to build sites for others? If you're a business owner, then I would recommend an all-in-one solution like MagentoGo, Shopify, BigCommerce, or Volution. All of those platforms come with video tutorials/step-by-step courses on how to build your site, have ample support, and provide complete documentation. But still be careful choosing courses online because there are so many scammers nowadays. In such cases I always use email validation tool.
Ep, glad to see you come back and tidy up...did want to ask a one day favor, I want to enhance my resume , was hoping you could make me administrator for a day, if so, take me right off since I won't be here to do anything, and don't know the slightest about the board, but it would be nice putting "served administrator osnn", if can do, THANKS