[waste_monk]

There's a ton of esoteric forums and sites, libraries of rare and old ebooks and documents, etc. . There's also the dark part of the dark web e.g. drug markets, financial services (spoiler alert: most of the "bitcoin tumblers"/laundering services and escrow providers are fake and will rob you) and other seedy stuff, I would very strongly recommend staying away from that kind of thing entirely.

Get on to the hidden wiki, it acts as a reasonable index of common stuff and has links to Tor search engines if you want to get specific. I would also recommend checking out the security section and learning to make sure you're using Tor in a safe and secure manner.

Get a liveboot Tails linux instance running (they provide the operating system on live DVDs you can run from disk, although you can also run it in a virtual machine if you want - but that is considered less safe) and make sure the Tor browser is set to Safest security level (click the little shield next to the address bar), which disables javascript and other things which can leak your identity. It degrades the user experience on some sites, but is much safer in terms of anonymity.