Anybody can give me a link to a video about how to use the addon or give example about how to use it on a boss.

1. Install the addon
2. Make sure it is loaded (char select screen, Addons button) when you are going raiding
3. Unless you want to configure bar placement, sounds, or other little things like that, you are done.

DBM and BigWigs are all about displaying information simply. There is some light reading to do on the DBM page that you may find helpful.

  Quote:

Originally Posted by zhengz

Anybody can give me a link to a video about how to use the addon or give example about how to use it on a boss.

When raiding Do I need to load any thing for boss or choose the boss?

No. DBM notices when you target or mouseover a boss, or when messages about a boss come through.  You don't have to do anything to get it to work beyond what the previous poster mentioned.