To ADD someone to your buddy list, click on their user name in any post they have made. Alternatively, you can click on About (in the site navigation bar on any page) and Who, then enter their name in the box that says "Find." When you are on their page, you will see:
Click on the start button next to "Watch List," and that user will be added to your buddy list, but ...
IF they also add YOU to their buddy list, they will now show up as a Buddy in your list, your "mutual buddy list." [Not an official site term ... used for clarity.]
If they DON'T add you, that user will appear as a Watched (stalked) user. The difference is that only Buddies (those who have also selected YOU as a buddy) will show up at the top of your screen when they are online ("mutual buddies").
To remove a buddy, simply repeat the process, and there will be a STOP button to remove someone.
Note: There is a limit of 100 users in your buddy list.
When you open your Buddy List, you will see a display of everyone you have selected, either mutual buddy or watched, at the very top. Next to these, you will see a colored button:
Green signifies On Line in the past 3 to 15 minutes
Below this, you will see another area with two tabs: Updated new topics started by buddies and Updated new topics started by watched.