Using release 11.04

I'm trying to get onto freenet, which requires java runtime environment to be installed.

I'm following the instructions here (http://www.java.com/en/download/help...selfextracting) but am getting an error message in terminal from the first step.

I downloaded the linux (self extracting file), the installation instructions say

"Change the permission of the file you downloaded to be executable. Type:
chmod a+x jre-6u<version>-linux-i586.bin
<version> refers to Java update version you just downloaded.
For Example: To install jre-6u30, above command will become
chmod a+x jre-6u30-linux-i586.bin"

So I paste that chmod a+x jre-6u30-linux-i586.bin into the terminal.

"chmod: cannot access `jre-6u30-linux-i586.bin': No such file or directory"

No idea what I'm supposed to do. Kind of losing it because I can't even get through step one of how to install a program. Very close to breaking the computer physically out of frustration, I already slammed my fist on it and part of the side popped open. Not the most constructive response I realize, so please if you wouldn't mind giving instructions as if you're instructing an ape. I mean, I can't even figure out how to make that bullet point next to chmod go away.

Getting back to it, if there's a way to install via software center, I haven't found it. Open JDK also gives me error messages while trying to install.