There’s no quick, straight-forward answer to your question. Coding a good HTML email requires learning HTML because the HTML email is, in essence, a web page you send to someone in an email. There are other gotchas too, like hosting the images (You don’t actually include them in the email. Instead, they reside on a server that you link to using HTML code).
I’ve probably designed and coded hundreds of marketing-related HTML emails, so it’s not a big deal for me. But then I’ve been designing and coding websites for over 20 years. For someone just beginning, like yourself, there’s a very steep learning curve that would take far too long to get into here.
Fortunately, though, there are easier ways to do it than code it by hand. I’ve never done it, but, yes, you can create a basic HTML email using InDesign (or so people say). I can’t vouch for this, but here’s some instructions I found with a web search: http://smallbusiness.chron.com/create-simple-email-newsletter-indesign-72883.html
There are also lots of YouTube tutorials that might work for you. There are also do-it-yourself, drag-and-drop HTML email builders online that you might try too.
If you want to do anything fancy, though, there’s not much choice other than to learn how to do a bit of coding, and that requires time to learn. Just because you can build it in InDesign does not mean that it can be recreated in HTML. Simple stuff, yes, sort of. Complicated designs, nope.