If you have been using other version control systems such as Subversion (SVN) or Perforce you should feel right at home, you will find a DVCS command set is very similar. The main difference between a central version control system and a distributed one is that the distributed system does not rely on one central server. Every person with a repository also has the full history of changes. Each repository is independent.
In Subversion, for example, each developer checks out a copy from the main server, works on changes, and commits them back to the central server. In case of conflicting changes made by other developers, the developer is notified and asked to merge the changes. In a DVCS world, things are different. Commits are local, and you can commit several dozen changes locally without ever communicating with anyone else.