I was told about this by a co-worker/fellow writer and I'm struggling to fully understand the process of this. Is there anyway to break this down to simpler terms and/or steps that will allow any writer to work it into their form of fiction and not necessarily a "hero" story?
A monomyth, by definition, has a hero and a journey and is thus a hero story. It involves a fairly long and complicated set of steps. I recommend looking at the Wikipedia page because it does a good job of explaining the monomyth.
As @thirdwind noted, if you don't follow the hero's journey, then it isn't the monomyth. You could pick up Joseph Campbell's "Hero with a Thousand Faces" to read about it.
I think the concept was first explored comprehensively in a book 'The Hero With a Thousand Faces' by Campbell, and more recently in 'The Writer's Journey' by Vogler. Both books are very interesting and insightful, I thought.
I agree with Steerpike and jazzabel. Read Joseph Campbell's The Hero With A Thousand Faces if you're interested in the monomyth. In fact, read it if you're interested in writing. Or literature. Or psychology. Or humanity in general. Or anything else - it's one of those classics everyone should read, just because.
As has been said, Joseph Campbell has a whole collection of works on the subject. The Hero With A Thousand Faces is a good place to start.