How to alter a script's content?

Hey there,
So I am trying to basically make a game with a script builder and I have a question about as to how I would alter or add something to the content of a script is there anyway I could be able to make it so you can add something to the content of a script. I would post a script to help you guys out however, I have NO IDEA where to begin at all I have no idea on altering a script's Content.... It would be greatly appreciated if someone can help me. This is not a request I don't care what you tell me about it. Anything helps right now I don't know anything about how to do it and yes, I've tried the wiki and looked at Script's API:Class and I think it has something to do with LinkedSource however.... I have no idea how I would use that to my advantage.

Thank you!