The process of making a programming language is basically the same as in any other programming language.
Design the language and all its features on paper.
Write a parser to take some text and convert it to tokens and then error check that there are no syntax errors.
As you parse it you’d want the result to be formatted in a AST or RPN stack. Basically some kind of structure to be able to refer to.
Then you’d need to run it piece by piece. The whole time you’ll be changing a program state.
Finally there’s a high amount of tweaks and polish you can add.
Do to the limited features of the event sheet you’ll have a bit more work to Add some features.
Basically there’s a lot to it. And how you do it varies greatly depending on what you want your language to be and do.
It’s interesting though, just not too trivial a project in many cases.