are you talking about the changing the gradient? if you want to change the gradient, upload your gradient to images/gradients for your style...then go to ACP styles & templates/style manager...in your style choose 'main css' , scroll down to 'category strips' and add the url to your gradient where it says 'background' ... something like this
url(images/misc/gradients/gradient_m.png) repeat top left
or seperating categories? here is one option for that...
https://vborg.vbsupport.ru/showthrea...light=seperate