Hey Nikolay, welcome to LU!
You can edit the script with any program you like. While you can use the common notepad, you can also go for Notepad++.
The scripting language is Squirrel, that means you have to learn it in order to be able to make your own scripts, you can start off by looking at how good scripts are made like
this or
this or
this or
this or
this or
thisThe Squirrel 3.0.x documentation is available here:
herePost any questions you might have in this thread, and if you encounter errors while coding, make sure to provide us the chunk of code containing the error and a detailed information about the error which is generated by the server. (you can post pics or simply the error text)