This theme is customizable using the standard WordPress theme customizer function.
You can access to the customizer visiting Appearance->Customize.
Here you can find all the list of available style customizations. For options not contained in the list, you may need to hire a developer.
The support service can’t provide CSS, PHP, JS or HTML code customization, as this service doesn’t belong to theme support service (such as when you buy a car, changing the default soundsystem is not part of the car assistance service).