Here is short list of intro links explaining how to work and manage Work Items in Team Foundation Server 2010 via Team Explorer (with screenshots).
TFS 2010 Work Items Basic User Guide – Introduction
TFS 2010 Work Items Basic User Guide – Create New Work Items
TFS 2010 Work Items Basic User Guide – Work Item Link Types
TFS 2010 Work Items Basic User Guide – Create And Use Queries
TFS 2010 Work Items Basic User Guide – Create New Work Items Out Of An Existing Work Items