Before I took my Java course at college I had taught myself javascript and found that it made learning Java a heck of a lot easier.
Use javascript to learn concepts like:
"for" loops
if/else statements
functions
arrays
variables
etc
You will see the same exact concepts with incredibly similar syntax. Although Java and Javascript are similar in name and syntax they actually have to relation to each other. Netscape developed Javascript because them and Sun Microsystems(developers of Java) were working together.
Ok anyways im babbling. Trust me that learning javascript now which is fairly easy to do will make your life much easier in your Java course.
Oh yeah and you can find many basic and advanced javascript tutorials at codingforums mother site:
http://javascriptkit.com/