Change de colour of buttons?

I do not want the red, blue or green, but brown one. I can not find css rule that could control the color and coming png in the folder I modified the style making new ones with the same name and size and not catch them. How I can change the colors of the buttons?.
Thank you.

Hi

If I'm not wrong than the button is using an image to set the color. Please show me Your site and tell me which buttons exacly You have in mind.

Hi. Already I found the problem. It lacked me for changing an image. Thank you

Hi

Ok. Glad You've made it working