Where do I start (my TDD quest) ?

[miguelmartins17]

While I was following the Javascript Tutorial I came across the Elmish section and as I don't know much about it I decided that it would be better before I went on to better understand this topic as it might confuse me later.

While I was reading the Elmish Repository it was necessary to create two files, but I didn't understand where I should create them or where they should be stored.