To add directories to your $PATH, add the following line to /etc/profile (For System Wide), or ~/.bash_profile or ~/.bashrc (For individual users):
Code:
export PATH=$PATH:/path/to/directory
To remove directories from your $PATH, you need to find where they are set, (In the above files, or some other places depending on your distro), and remove the entry from the export PATH line.
I hope this helps
--Ian