A project that begins with a person, the best way is to put it as an open project, and try to join a community.
You create a repository in GitHub for your language project - put the code, and the documentation: the documentation must be very complete, of justification, to the specification of the language itself, without worrying about the code, and finally, the documentation of your code.
Of course GitHub is just the most used system - but it is important that it be both open source and a public repository - the service can be bitbucket, an instance of gitlab, etc ...
Now, newly created languages that have had a relatively quick reach have one thing in common: all were created by multibillion-dollar corporations - go, kotlin, swift - for example. It's another kind of launch, when you have the chance to employ dozens of full-time professionals to create your language - including the marketing team to create outreach campaigns.
An important factor is whether your project will actually have some innovation - filling a niche that does not exist in the language spectrum, or if the goal is just more didactic: for your learning and who to get involved in the project. There are very good languages in the first category to be forgotten, even after some initial traction. Or have you heard of "Boo", a statically typed language with the Python-based syntax that runs in the .net VM? In the second category, the project will, at least in the initial months, be restricted to a small circle of users anyway.
