"Racket (formerly named PLT Scheme) is a general purpose, multi-paradigm programming language in the Lisp/Scheme family. One of its design goals is to serve as a platform for language creation, design, and implementation. The language is used in a variety of contexts such as scripting, general-purpose programming, computer science education, and research." - https://en.wikipedia.org/wiki/Racket_(programming_language)
If you've downloaded the command-line client and have Racket installed on your machine, then go ahead and fetch the first problem.
exercism fetch racket
In order to be able to submit your solution, you'll need to configure the client with your Exercism API key.
exercism configure --key=YOUR_EXERCISM_KEY
When you've written a solution, submit it to the site. You'll have to configure the command-line client with your exercism API key before you can submit.
exercism submit PATH_TO_FILE