How change the color in menu?

Hi, i want to change the "pink" color to "red" , what code i have to change?

Thanks a lot!

Im talking about this pink element:

That is templates/ot_boutiquebox/images/blue/mainmenu-active-bg.png
You can use photoshop, open this image and change color of it.
Or
You can also use photoshop and open the .psd design we provided in the package, then change color and cut the image.

Thanks a lot!!