Action Details
Requirements and how-to articles for Steam's action:

Sign up for Steam Direct in order to be able to distribute games/software on Steam.

You need this to get it done:

Steam Account
A Steam account is required in order to begin the process of signing up for Steam Direct.
Company Information
You must provide accurate up-to-date identification of the legal entity/company whom you are representing when signing up to publish content on Steam. However, if you as an individual own all of your game/software's content, you can register as a "Sole Proprietorship."
Tax Information
You will have to fill out a brief tax questionnaire to determine your tax status and withholding rate.
Payment Information
Steam requires accurate bank information (routing number, bank account number, and bank address) so they know where to send payments from sales of your application. (The account holder name on your bank account must match the name you provide when onboarding.)
Requirements missing or found errors? Report

How-To Articles
A list of useful links for you:

Steamworks - Documentation Home Page
Information about getting started using Steamworks.
Link missing here or found errors? Improve How-Tos