I need help installing processing for a class of fine. I have tried following this post, but it is a little old, and I get an error in terminal when I run
cd processing-1.5.1 ./processing

This is the error:
Could not find the main class: processing.app.Base. Program will exit.
I've download the newest version of processing, but it is a .tgz file, and I have no idea what to do with it. I've tried following some articles online on how to install .tgz files, but still being a noob to ubuntu, I can't get it to work. Any help would be appreciated.