Let's say I have a Joycean-level masterpiece in a .txt file on my laptop. What steps would I have to take to get it published.
Copy paste it to whatever word processor you are most comfortable with, be prepared for the lag.
Look up novel formatting guidelines on the internet and format your novel according to those guidelines. 1-inch margins and all that.
Write a good query. You can read plenty about writing query letters on the internet. Work hard on this: this is your elevator pitch.
Buy a copy of Writer's Market and submit your query letter to agents. Some agents may also want you to submit a sample of various lengths.
Based on your query and how much they like it, agents will ask for a partial manuscript or a full manuscript.
If they like it, agents will accept the manuscript.
Now it is up to them to work with you on getting your manuscript published by the best publishing house they can find for that work. They will take a cut of whatever you make.
If you actually have a masterpiece, do the above.