pzykie your issue is this, the path you typed is not valid. Either of the following should work.
Code:
cd ./apache-tomcat-5.5.28/2/webapps/pwAdmin/addons/Maskgen
or
cd /opt/apache-tomcat-5.5.28/2/webapps/pwAdmin/addons/Maskgen
Using "./" means that its in your current directory. "/" means its the root of your drive (ie the highest point of the file structure). Using ".." will move you up a directory.
Also take note of uppercase and lowercase letters.
This is Bash
http://en.wikipedia.org/wiki/Bash_(Unix_shell)
Basically bash is trying to execute the command "cd" but it errors because you gave it invalid arguments.