On the
Releases section, download the UjAPI.zip file and unzip it. Inside it contains the UjAPILauncher.exe.
With the launcher, you can set the Warcraft III executable and World Editor that you want to use. When you open World Editor or Warcraft III with the launcher, it will load UjAPI on top of these two programs, enabling you to use or play with its added features. Without the launcher, you can play as normal.
All the functions that you can use are listed
here.