To spell it out, follow these steps.
1. open a terminal from your program menu
2. Type 'nano -w ~/.bashrc' - this will open the .bashrc file in the nano editor (easy to use text editor).
3. After adding the lines you want to, type CTRL-X and choose to save the file.
4. Next, type 'source ~/.bashrc' as this will re-read the .bashrc file.
5. Type 'env' to see your environmental variables. You should be able to see your new variable.
6. You can now use that terminal session with your new environmental variable and it will be there for any new sessions you have open. To start with a clean slate and make sure everything you are working on has the new variable, logout and log back into the system.
You can also edit /etc/profile in the same manner described above as the root user and this will make the variable available to all users.