The mod supports Fabric (*) mod loaders. Follow either mod loader's installation guide, then download the mod file for your Minecraft version, and install it into the .minecraft/mods folder.
Run the game once to create the configuration file. By default, the window title will be set to Minecraft . Unlike in vanilla 1.8.9 onwards, the title will not change when you enter a world/server.
To change the title or icon, navigate to the .minecraft/config folder, and open customwindowtitle-client.toml in a text editor. You will see the following entries: