how to write to weblogic log files using a servlet, servlet debugging

Hello, I have a java servlet running on linux weblogic 6.1 that gets request from JSP and processes them. I like the servlet to write to the weblogic logfiles in the log directory. I tried System.out.println("message"), System.err.println("message")  etc none of them works. I know there is some simple built in comman to do it, just cant find it.

Also in general, is there any way(besides writing to log files) to debug servlets in weblogic WITHOUT using fancy tools like jbuilder. Since system.out.println doesnt seem to output anything, I have no way of putting in some debug messages.  

Thank you,

gaga