There are two interesting parts to an S1 (or a 10K):
* a qualitative description of the business, as the management sees it. I find this super interesting and it's usually in the middle of the document - look for "management's discussion and analysis ..", or go here: https://www.sec.gov/Archives/edgar/data/1561550/000119312519...
* the quantitative part. There are three key, but interrelated concepts to learn. The income statement, balance sheet, and cash flow statement. A intro course to accounting should be great, I can recommend this one: https://www.wallstreetprep.com/self-study-programs/accountin...
Hijacking this to maybe also get a recommendation -- For the purposes of better understanding S1s, I've been trying to find a good non-textbook to understand corporate finance in general. Anyone?
I've similarly wanted to start learning some basics of reading financial statements. A friend of mine in a financial role recommended the book _The Basics of Understanding Financial Statements: Learn How to Read Financial Statements by Understanding the Balance Sheet, the Income Statement, and the Cash Flow Statement_. When asking how to "read and understand an S-1", I assume you mean the financial statement figured within, so I think that book may be beneficial to read, although I've not yet read it. If someone has further recommendations geared towards S-1's or other financial statement reading that would be great!
Take an introduction to accounting course (https://www.coursera.org/learn/wharton-accounting is very good, and it's free to audit), and you should be able to understand the meaty part of S-1 (and 10-Q/10-K)
Learning how to read a document and interpreting what it means are two different things. For the former you can learn how to do so from (almost) anyone who already knows how to do so. Your interpretation of the document might also vary from whomever taught you how to read it.
