Step 1.) Install Tor and the Torbutton Firefox extension.
Alternatively, just use tor2web and miss out on tons of content.
Step 2.) Start Tor, connect, and activate the Torbutton.
Step 3.) Start visiting deepweb sites! I won't link to a ton because of forum rules, but here's a link to the Hidden Wiki. Another good place to find them is Reddit's r/onions board.
If you have any questions, I'm a seasoned explorer of a lot of deepweb sites and can probably help you find what you're looking for. Don't hesitate to private message me for more personal questions!
Pictures of some of the tamer content you'll find on the deepweb: