As long as your text is at a safe distance from the edge of the page - you're fine. Or any material that is intended to be viewed by the reader- this needs to be in the "Safe Type Area" as illustrated above.
You can talk to your printers about this safe area.
Bleed area is there for the printers - talk to them about how much you need. This is the area for anything that needs to be right on the page edge, it needs to extend past the page edge for trimming purposes. You need to ensure that these items extend from the page into the page area.
Slug area - that's more for technical information to relay to the printers. For example, I might create a "spot uv" and have it "bleed" off the page. But I might put "SPOT UV ONLY" in the slug area so that the person operating the printing machine can see that information.
We used to have secret communications with the printers for a bit of fun, "What are you doing this weekend, we're thinking of going to a festival!" and this would appear on the printed sheet outside the bleed and outside the print job.
Needless to say, once the foreman saw our little communications on the print sheets he had strong words with us. But we retaliated with "Geez lighten up!" on the next job
I'd like to come at this from a slightly different angle. If the job you are to produce has a small print run, and is relatively unimportant, then fine learn on the job. But if the job is important, perhaps vital to the success of a business and costing a lot of money to print, then I would suggest you go to a professional designer. Things can easily go wrong, or look amateurish, if you don't know what you're doing in the world of professional publishing and printing.