cd-helper: command not found

Maybe Your $PATH variable doesn't contain the default paths? echo $PATH should give something like:

[root@server ~]# echo $PATH
/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin

If it's empty, You may set the PATH variable with this command

export PATH="/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin"

On Debian possible default full paths are:

/usr/share/openacs/bin/cd-helper - from package: openacs

You may install the required package with command apt-get install {package}

Error in other languages:
cd-helper: bevel nie gevind nie
cd-helper: comandă negăsită
cd-helper: comando não encontrado
cd-helper: commande introuvable
cd-helper: command not found
cd-helper: käsku ei ole
cd-helper: không tìm thấy lệnh
cd-helper: komanda nerasta
cd-helper: Kommando nicht gefunden.
cd-helper: kommandot finns inte
cd-helper: komut yok
cd-helper: nie znaleziono polecenia
cd-helper: níor aimsíodh an t-ordú
cd-helper: no se encontró la orden
cd-helper: no s'ha trobat l'ordre
cd-helper: opdracht niet gevonden
cd-helper: parancs nem található
cd-helper: perintah tidak ditemukan
cd-helper: príkaz nenájdený
cd-helper: příkaz nenalezen
cd-helper: команда не найдена
cd-helper: командата не е открита
cd-helper: 命令找不到
cd-helper: コマンドが見つかりません