What should I learn?

Hello all,

I am a newcomer to the world of Java. I'm training for a job that needs me to provide system support to web applications that run on Java EE technologies.
In college, I've learnt to write code. But, as you can see, my job does not need me to code. I need a whole new skill set that I am trying to discover.

In my first few days of training, all I did when something went wrong was to restart servers (JBoss and Tomcat). But once my supervisor made me watch him work, and he did stuff like analyzing thread dumps, messing about with protocols and reverse proxy configuration, investigate memory leaks and so on.

I will soon be trained to do most of this. But I'm looking to study some stuff and improve myself. My questions are:

1. What skills do I need? What do I start learning? I need to be able to go to a system in a production environment that has issues and know what to do to investigate and fix those issues.
2. What books do I need to read to get these skills?

This is my first post in this forum. I hope you folks can help me get started.

Thanks in advance!