Tekkit Classic Server 3.1.2 Problems Launching

[brodster121]

I have been trying to launch a server but it keeps saying in the cmd panel:

C:\Users\owner\Desktop\Tekkit Classic Server>java -Xmx3G -Xms2G -jar Tekkit.jar

nogui

'java' is not recongnized as an internal or external command,

operable program or batch file.

C:\Users\owner\Desktop\Tekkit Classic Server>pause

Press and key to continue...

and when i do is closes the cmd panel, can anyone help me? please.