set the PATH in your environment:

use "$PATH" to show your path (assuming you are using bash)
use "export PATH=$PATH:[path to your JavaVM]" to set your path

your JavaVM might be located at

/usr/lib/java/bin
/usr/local/lib/jre/bin
/usr/lib/jdk1.4.0/bin

or a similar directory, it depends on which distribution you are using...