1. Open a terminal and navigate to the folder where the tar.gz file is located. From your description I'd guess it's in ~/Downloads.
2. Type the following command:
Code:
tar jxvf {correct name of the tar.bz2 file}
(what you typed in your post above is not the correct name)
3. Move the untarred folder produced by the above command to a location of your choice, typically this would be in /opt.
jdk