There are several topics on how to learn ruby and RGSS3 in this forum where you posted, and you can follow the links they give for websites that teach ruby (RGSSx are variants of Ruby and don't have their own basic learning sites).
If you're asking for the script editor of Ace to write and test your own programs, then I suggest you follow the link "how to use a script" (or even the "starting point") in my signature, because they will guide you to those basics.