I’ve been using Renoise for about a year or so, and after joining this forum I heard about scripting.
I sound totally stupid for asking, but where can I find where ever you can add or edit scripts? 
Look here:
currently, you have to be a registered user in order to access the scripting feature, since it is available in Renoise 2.6 which is currently on beta stage so it can only be downloaded if you have bought Renoise