I am new to ExtJS. I tried installing it as per the steps [`given here.`](http://www.sencha.com/learn/getting-started-with-ext-js-4)

But I am getting one error while running this command.

```
   sencha create jsb -a http://localhost:8080/helloext/index.html -p app.jsb3

```

Error msg :

> 
> C:\Program Files\Apache Software
>  Foundation\Apache2.2\htdocs\helloext>`sencha create jsb -a` <http://localhost:8080/helloext/index.html> -p app.jsb3 'sencha' is not
>  recognized as an internal or external command, operable program or
>  batch file.
> 
> 
> 

What is the problem ?

PS : I already done with the prior steps of installing Apache Server and unzipping ExtJS SDK.

Thanks.