I'd like to say something snarky like, " Sorry, we'd like to help but we only make knives here" but I won't.
Instead, I'll try to answer your questions but with only one picture to work from it will be mostly guess work.
Since the knife isn't actually real the question isn't "how is
that knife made" but rather how can you make something that looks pretty much like that. In the real world, if that 'knife' were produced by Frost cutlery or some similar outfit that makes such fanciful creations, that piece you have marked and the entire guard would likely be one piece of cast metal. Its entirely possible that the entire handle and guard would be a one piece casting. I saw a cheap Chinese knife once that looked exactly like a large lockback folding pocket knife, complete with release and hollow body for the blade to fold into. But, it was a one piece casting. So, all that stuff that looks like a tang and a sort of pommel probably wouldn't be.
Back in the real world now, if you actually wanted to make a sort of real version of that thing you'd probably have to learn to cast some parts or spend a great deal of time with some good files. The problem, of course, is the handle - it is way too complex for anyone to specify any simple way to make it. Its going to be very difficult to make no matter how you go about it. To your specific question concerning the tang I can think of several ways to deal with the tang depending on how you plan to make the rest of the handle but I can't say for certain how
that tang is made because it isn't real.
For part 2 of your question, all of that other stuff would be separate from the blade steel. You would never try to make anything like that directly from blade steel ...