If you find that you're still lost, have no fear. You can find additional help and research guides at the Mercer Law Library website.
Another great place to start is with Jeremy Simpson’s Federal Income Taxation - Beginner's Research Guide: Introduction. This guide will give you a great foundation along with helpful information on where and how to find tax forms and other resources.
The New York University Law Library offers a very robust tax research guide with the Federal Tax Research: Outline & Guide Information. Once you have an idea of what you need to be looking for, this research guide will point you to a number of comprehensive sources. Some of the listed resources require a NYU student subscription access, but there is still plenty of resources for you to choose from.
The University of Florida Levin College of Law also offers a Tax Law Research Guide, especially if you are looking for more substantive tax issues that are not covered in this guide.
https://www.taxpayeradvocate.irs.gov/
The Phillip C. Cook Low-Income Taxpayer Clinic website is second to none in terms of the topics that it covers and tools that it offers. You can find substantive information on issues specific to low-income taxpayers, get a plain-language overview for the basics of federal income tax procedure, and, most importantly, a great collection of forms and guides.