Import subsite via powershell

Hi,

I would like to import a .cmp file that's a backup of my subsite.
Now on my new Site I would like to do this restore of this subsite. 

Via powershell : 

Import-SPWeb http://tes:666/stage -Path C:\Default3.cmp -Force

What am I doing wrong? Thx

This is my error : 

The term 'Import-SPWeb' is not recognized as the name of a cmdlet, function, script file, or operable program. Check th

e spelling of the name, or if a path was included, verify that the path is correct and try again.

At line:1 char:13

+ Import-SPWeb <<<<  http://stspdev2:650/stage -Path C:\Default3.cmp -Force

    + CategoryInfo          : ObjectNotFound: (Import-SPWeb:String) [], CommandNotFoundException

    + FullyQualifiedErrorId : CommandNotFoundException