Java APIs

Hello, I've usually never had problems with java until now and I will greatly appreciate it if you help me "for free" unlike Oracle which charges you 5$ per minute. >.> Seriously?
On to the problem, recently I decided to make a tekkit server(Tekkit is a modpack for a game called "Minecraft"[Ring a bell? It was coded in Java]) but when ever I launch the program it gives me this error:

C:\Users\Erik\Desktop\Server>java -Xmx1G -Xms1G -jar Tekkit.jar nogui
'java' is not recognized as an internal or external command,
operable program or batch file.

C:\Users\Erik\Desktop\Server>pause
Press any key to continue...

Now usually reading errors and finding out the problem isn't hard for me due to the fact I code in Java, but this one stumps me. I believe it gives me this error because I'm missing something from Java but I'm more than confident that I have everything I need installed. Am I missing something? If so please do tell.