unpack tqz on server?

can anyone tell me how to solve this?

used ftp to transfer cscart_v2.1.2-professional.tgz to httpdocs folder.

when I try to unpack, I get this:

Error: Unable to show file /httpdocs/cscart_v2.1.2-professional.tgz: Unable to read the file or the file format is not supported.

Contact your webhost. From what I can tell - You are using a windows server, which do not have native support for .tgz files.