Font color

Hi,
I just used your plug in and it works wvery well.
I have just an issue: the font color is dark grey on a black background, so it’s difficult to read what you’re tiping in the form.
http://www.6pmstudio.com/opinioni/
Can you give me how to change the font color?
Somebody’s suggesting to work on CSS but I have no experience at all about it.
The website was not created by me and I’m ust trying to modify something.
Thanks

http://ww.wp.xz.cn/extend/plugins/gc-testimonials/