UNIX for Dummies Questions & Answers

Hello,
When i attempt to install Java. I get this error code

Can someone tell me what im doing wrong.

you don't have permission to either clobber the file ./jre-6u24-linux-i586.bin OR
if it's a directory, to create files in it.

Just make that file clobberable:

chmod 777 ./jre-6u24-linux-i586.bin

I was trying to upgrade my java 1.6.0_20 to java 1.6.0_24 as a self-learning experience. Felt nervous and want to know the right way. Yes, I downloaded the file from SUN:

Code:

jre-6u24-linux-x64.bin

and executed it. It was successfully installed in my local folder

Code:

/Downloads/jre1.6.0_24/

But, when I check the version it still displayed the old version which is linked the java executable by two symlinks after I recursively checked each file (for simplicity I put them directly here):

Code:

$ java -version
java version "1.6.0_20"
$which java
/usr/bin/java---> /etc/alternatives/java--->/usr/lib/jvm/java-6-openjdk/jre/bin/java

Now, my question is: can I replace the old java executable with the new one, or simply replace the whole folder that contains the java executable? I am aware there some new files. Not sure the whole story while I am trying to understand the basics.
I am using Ubuntu 10.10 Maverick Meerkat - released in October 2010 amd64-server in linux kernel 2.6.35.27-server & gnome 2.32.0.
Please someone give me a explanation. Thanks a lot!

Yifang