Whisper reminds about other well known social networks, but may differ in some ways. Here is a short description over the concepts of using Whisper.
Use your own full name during the Whisper registration. The name is the only way for your friends to locate you, and you want this to be both correct and preferable quite unique. If you have a middle initial, please use it as well (e.g Mikael Q Kuisma). The name is not possible to change once registered.

Every user in Whisper got a News feed and a Log. The News feed is focused on your circle of friends, and the Log on the current user.
Most often you write your own status updates in your News feed, and say hello to specific friends in their respectively Log. This is also the default.
Sometimes it may be good to write in friends News feeds as well. When you first register at Whisper, the only friend you got is Whisper Rendezvous. Visit him and present yourself in his News feed. This way, all other newly registered uses can see you exists, and chose to befriend you.
Your log will also display your activities at other places.
The only way to find a friend, is via a common friend. Because of this, all Whisper users start with the imaginary friend Whisper Rendezvous. Use Rendezvous Log to find your new friends. Once established an own circle of friends, there is no need to still be friend with Whisper Rendezvous, but until you have enough friends to guarantee that at least a few of them are online and reachable, imaginary friends like this are good to keep.
You can comment any post, even other comments. The comments are shown in a tree like indented structure. The comment is visible to the same people the original posting is visible to, not necessary all your friends.

If someone updates an old posting, not currently visible, the “You got news” will light up. Pressing this button will take you to the first unread updated thread, with the new comments highlighted in yellow. New original posts will not trigger this, since they are at the top of your news feed anyway.
If you read a particularly interesting post, you can share it among your friends. Just because you got it, it does not imply all your friends got it - but by pressing “share”, you will repost this in your own News feed as well. (Not implemented yet, can still not decide if this is a good feature or not)