By default Outlook 2010 does not have an Archive file, one has to be created manually. Once the file has been created, you'll need to check the AutoArchive settings to see if the default settings meet your needs.
Select: File > Info > Cleanup Tools (Mailbox Cleanup).
Click on Archive in the dropdown box.
In the window that opens you can change the settings to Archive:
All your folders and subfolders.
A single folder and all its subfolders.
Set Outlook to Archive everything before a specified date.
Click OK and the Archive file will be created and attached to Outlook.
The Archive process will then run using the settings you previously entered. All email received before the date you selected will be moved to the Archive file. If the email being Archived is in a folder named John Doe, it will be stored in a folder named John Doe in the Archive file. If a folder does not have email old enough to be Archived, the folder will not be created in the Archive file until it does.
Note: To see if the Archive process is running, look at the lower right-hand corner of the Outlook screen.
When the Archive process has finished, right-click on the Archive and select Close"archive".