mpic++: 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/mpic++ - from package: mpich2-devel
/usr/lib64/mpich2/bin/mpic++ - from package: mpich2-devel
/usr/lib/mpich2/bin/mpic++ - from package: mpich2-devel
/usr/lib64/mpich/bin/mpic++ - from package: mpich-devel
/usr/lib/mpich/bin/mpic++ - from package: mpich-devel
/usr/lib64/mvapich2/bin/mpic++ - from package: mvapich2-devel
/usr/lib/mvapich2/bin/mpic++ - from package: mvapich2-devel
/usr/lib64/mvapich2-psm/bin/mpic++ - from package: mvapich2-psm-devel

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

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