Programming via Java

I am a freshman in college and have to use NetBeans for java in order to do my homework and projects. But i need something else to run it, besides just the program. can someone tell me what i need and how to get it? possibly a link. thanks in advanced

Yes download it from sun's website, not netbean's website. Netbean's website does not include the java jdk. Oh and I do like netbeans for java, it's nice. My buddy preferrs eclipse, but there really isn't much difference.