Making a Scripting gui, would like a general idea on how to run code with out using load string?

so, I'm making a scripting GUI almost like a script builder, except your just coding I know how to make the guis work, that's not the problem, is the execution of code, and trying to make the texted colored, for example, local would be blue just like in-studio white version theme, and print would be blue parentheses would be yellow string text purple etc. I'm making this just for fun, and I'm trying to become better at scripting by doing this.