Add basic text?

Is there any chance i can add a text field (for some basic user information) after a user has clicked a specific checkbox option? I know how to work with rules but i can not find any field on which i can type in information only. I need a text (a large one) to appear after someone has clicked a specific icon.?

That text should not give any input options but instead just appear after a user has clicked a specific field (checkbox). The only thing I find is the text area – but there a text field FOR THE USER appears. I just need a normal text field on which I can write down some text.

I just find fields like adress, e-mail etc but i can not find a way to simply output a text. How can i do that?