Welcome to the Bunnings Workshop community @WK71. It's amazing to have you join us and many thanks for your question.
Building a Colorbond fence on flat ground is an easy process. However, on a slope, it can be more difficult. You can either go with a stepped look or a sloped approach. When stepping the panels, it creates a staircase appearance and gaps can be noticeable under the panel at one end. When creating a sloped fence, you might need to cut the panels to suit, and if you are not confident in doing so, it would be worth employing a professional's services.
The amount of fall over the slope can determine the best approach. If you'd like to post some images of the area, our helpful members will be able to give you their opinions.