Visual Studio Code Extension

This is the fastest and easiest way to get started with TLA+ and TLC.

Download visual studio
Search for the tla+ plugin in the extensions tab.
Make sure to install TLA+ Nightly. It is usually stable, it has more features and extension release is lagging behind.

Additionally, you might want to enable automatic module parsing on saves: https://github.com/tlaplus/vscode-tlaplus/wiki/Automatic-Module-Parsing

Resources

The plugin source code can be found on github: https://github.com/tlaplus/vscode-tlaplus