MAC OS X , i need some help, please

I changed the skin, and now i use MAC OS X. Everything is perfect, but i can't change the fonts from right click on desktop, and start menu.
I attache here 2 images.
Please tell me how can i change it to arial, no bold.
Thanks.

What do you mean you use OSX?

Misleading title, but he means he uses the theme named "OS X". I think...

Do you know how to modify the size / fonts from this menu ?
I mean " right clik- desktop "
Thanks.

Where can you get this theme? PM me:) Any assistance is appreciated..