I think what you are asking is how to become somebody's fan. Well, if you are reading their hub, just look at the top right of the hub and you will see the profile pic of the hubber. Just below the picture, there will be a link for you to click that says: "Join xxx's fan club" Just click on the link and you are automatically a fan.
If you are viewing a comment that they left, just click on their picture and you will be taken to their profile. There will be a similar fan link there.
Hope I answered your question. :)