See https://www.nmra.org for model railroad information. It includes an extensive Beginner’s Guide to help.

Guide content includes 1 Getting Started, 2 Layout Planning, 3 Building Benchwork, 4 Laying Track, 5 Adding Power, 6 Scenery, 7 Structures, 8 Motive Power & Rolling Stock, 9 Operations, 10 Weathering, 11 Tools, and 12 Special Focus Layout Themes.
Your first decision is what scale to use

HO-scale is the most common and then N-scale and if you want it outdoors you need G-scale.
For parts many retailers have moved to the Internet and provide online catalogs for browsing and making purchases.
The most popular commercial model railroading magazine, and good for the beginner, is “Model Railroader“, published by Kalmbach, which can be obtained close to the date of publication via subscription at https://www.trains.com/mrr/subscription-plans/.
https://ser-nmar.org
Smoky Mountain Division Monthly Meetings – The Smoky Mountain Division is alive and well. We continue to meet in-person on the first Thursday of odd-numbered months at the Shoney’s Restaurant 4020 Rutledge Pike, Knoxville. We are also meeting via Zoom on the first Thursday of each even-numbered month. We average around 15 for the in-person and 5 or 6 for the Zoom meetings. https://www.facebook.com/SmokyMountainDivisionNMRA/