wmaker.inst: 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 CentOS possible default full paths are:

/usr/bin/wmaker.inst - from package: WindowMaker

You may install the required package with command yum install {package}

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