How do I start publishing when my job is not research related?
To be honest, I think it would be extremely difficult to publish independently, in a forum that would matter.  That is, there are predatory publications that will take just about anything, including a publication consisting solely of the repeated sentence Get me off Your F--king Mailing List ... but if you want to publish real work, there are a lot of hurdles.

I'm not going to google for you to point at how-to's that must say things like how you need to state a thesis, provide background, do some evaluation, compare to prior art, and so on.  I don't think the issue is the mechanics of writing a paper, though the English in your original post indicate that will be a problem if you publish in English.  (I sympathize with those for whom it is not their first language, but it doesn't make it easier to publish.) 

The issue is really, as a junior software engineer, is it really true that you can could squeeze some of [your] knowledge into some kind of publication?  

It's surely the case that some people have published with minimal background and sometimes even made monumental contributions.  But the bar goes up with time.  There's a lot of cumulative work.  If you really think you can add to that, you probably should start with the "prior art" part I mentioned before.  Read a bunch of papers, for instance in a conference pertaining to your area of interest, and see if there is something there where you think you can add on to it.  

But I think a better approach is to do accomplished work as a software engineer, then apply to a PhD program, and have the professors teach you what is involved in publishing.