Paths are the locations for executables which can be accessed from any location.

To view current paths[-][--][++]

# echo $PATH

To add to the path (lost upon restart or shutdown)[-][--][++]

# PATH=$PATH:/dir/dir1

Example[-][--][++]

I downloaded UNace (an .ace acrhive extractor)
I copied the unace folder to /usr/bin/
I added a path:
# PATH=$PATH:/usr/bin/unace

now I can type unace anywhere, and it finds it from the path

To Add a path permenantly (loads at startup)[-][--][++]

To edit a path for a user open $HOME/.bash_profile or to edit for all users edit /etc/profile
In either file you will see: PATH=$PATH:$HOME/bin, just add paths to that, separate paths by a :

PATH:$PATH:$HOME/bin:/usr/bin/unace