I have the latest version of ubuntu on my laptop and i use opera and mozilla web browsers on GNOME desktop environment.

I downloaded and installed java but it doesnt work. I open websites with java games in Opera and Mozilla and it still asks for plugins. I installed java from a bin file from the java website.

Also LimeWire doesnt work if i type limewire in the terminal this comes up:

Starting LimeWire...
Java exec found in PATH. Verifying...
OOPS, you don't seem to have a valid JRE. LimeWire works best with Sun JRE available at http://www.java.com
OOPS, unable to locate java exec in /usr/lib/ hierarchy
You need to upgrade to JRE 1.4.x or newer from http://www.java.com
ls: /usr/java/j*: No such file or directory
OOPS, unable to locate java exec in /usr/java/ hierarchy
You need to upgrade to JRE 1.4.x or newer from http://www.java.com
ls: /opt/j*: No such file or directory
OOPS, unable to locate java exec in /opt/ hierarchy
You need to upgrade to JRE 1.4.x or newer from http://www.java.com

Im not sure if the files are in the right place.

What do I do?!

You should have followed the Ubuntu Java HOWTO. Try working through it, and then if you have any problems ask.

Remember that Ubuntu has loads of documentation and HOWTOs to help install/setup many common programs. Most of it is located in the Community Docs section of their website.

Good Luck
~Justin