The Visual Studio 2008 docs are still online. The Unshelve button is hidden in the Pending Changes window and in the File->Source Control menu in the top-level menu bar of visual studio.
Whereas you can restore a changeset into a workspace using the Get command, you must use the Unshelve Command to restore a shelveset. You can use the Unshelve button in the Pending Changes window to restore one, some, or all the pending changes in a shelveset to your workspace. For more information about the Pending Changes window, see How to: Check In Pending Changes. When you unshelve all the changes in a shelveset to a workspace using Visual Studio, the pending changes information with which the items are associated is restored to the Pending Changes window also.
See: Shelve and unshelve pending changes
Generally, when the UI is confusing, consider falling back to the commandline tools:
From any folder in your workspace from a visual studio command prompt:
# List Shelves
tf shelvesets
# Unshelve
tf unshelve "shelveset name"
You can also use a newer version of Visual Studio to do your source control interactions and develop from Visual Studio 2008.