how do you follow someone?
On the web version, simply use the search box in the upper right corner to search, then select the button to follow. On mobile devices, go to friends and search.
i only see 'add friend' on someones profile page...not follow
When you click that button, you follow the person. "Friends" on your profile are the people you follow, "Followers" are the people who follow you (i.e. they've clicked the "add friend" button on your profile)