WPCF& – Where is the CSS?

Hi,
I have just downloaded and installed the latest version of WPCF7. I watched a couple of tuts and on one of the the guys went to the plugin and opened the edit link in the WP-ADMIN area. At the bottom of the editor they had a page called style.css.
They opened and copied and pasted the css into their child theme css. I carried out the same steps but when I get into the edit area I see all the pages on the right hand side but I cannot see a file for style.css for the WPCF7 form.
I just want to make the message box less tall when it sits in the sidebar. Instead of it being 10 rows, I just want it to be 5 rows.

I would also need the style.css file in order to re-arrange the necessary fields when I want to style the form to my own liking.

All help gratefully received and appreciated.