How to change my "channels & interests" on an Android phone?

I have an Android phone and get some news based on my "channels & interests" when I swipe from the main Home Screen to the left. How can I add a new topic to these "channels & interests"? I found this site which does not really help. In *Step 2: Choose what updates you get* it does not explain how to **add** a new topic. I only can view some list I can choose from. Is there any way to really implicitly, directly and clearly add a new topic to that list?