In the default TFS setup there are three work item types: scenario, task and bug. That last one is quite straightforward, and task also: it\'s a specific job for a team member t
You can think of scenarios as representing the users perspective, whereas tasks are the developers perspective. According to the MSF Agile documentation a scenario "represents a single path of user interaction through the system you are building.", and a task "identifies a specific item of work for a team member to perform."
Tasks can be linked to scenarios. When checking in you, as a developer, have solved a task, not the scenario, so you should relate the changeset to this task.