Well I think the question is 'WHAT' do I file, not 'How' do I file.
You file with whatever forms the IRS requires to report your income.
Sometimes these forms are simple, like a wage earners [w2], social-security earners [1099-sa], blah, blah, blah.
Sometimes it is difficult, like a business owner, w multiple investments, foreign & domestic, properties, stock & bond holdings, real-estates stuff, and a lot, lot more.
So the forms you need to properly file, are dictated by the types of income you generate.
Good luck trying to understand this, because the IRS simply 'tries' to understand and implement the laws that congress 'tries' to enact.
If this all becomes too overwhelming, simply disregard the baggage & make your own rules for taxes like the former president did. Hmm. Why would he not release his taxes as most candidates & serving presidents do?
I digress. The question was what not how. Both are very vague.
