Tor is the encryption program people use to navigate the dark web.
Generally, people who purchase anything on the dark web first move Bitcoins (or their cryptocurrency of choice) from the Bitcoin exchange into a heavily secured wallet.
To help with this, there are wikis that collect various dark web sites or directories that are (relatively) popular stops and good places to begin.
Browsing the dark web can leave you especially vulnerable to such attacks by hackers and other criminals.
While on the Tor browser, avoid any other activity on your computer — keep everything shut down.