WARNING: This old version is vulnerable to the Log4Shell exploit. Do not use this in multiplayer without a patch.
Added Radar mod: Shows the location of nearby entities.
Added a “Speed” slider to Freecam.
Added a “Tracer” checkbox to Freecam: Draws a line to your character’s actual position.
Added a “UI Settings” window that allows you to customize the opacity, background color and accent color of the ClickGUI (including Navigator & TabGUI).
Added Realms support. (MC 1.12 & 1.12 OF)
Added tooltips to Navigator.
Added a default keybind for the window-based ClickGUI: RCONTROL.
Fixed the window-based ClickGUI not rendering blocked features in red. Also added a tooltip to explain why they are blocked.
Basically just run the installer. See this tutorial for details.
Also, this should be obvious, but you do need to have a licensed copy of Minecraft Java Edition in order to use Wurst. Wurst is a cheat client, not a pirate client.