i don't know if here is good section for this topic
so, i have installed net-snmp with macports.
I have configured snmp with snmpconf -i.
I launched the snmpd service.
when i run this command:
snmpwalk -v1 -c public localhost

i have this result :

SNMPv2-MIB::sysContact.0 = STRING: "Administrator <postmaster@example.com>"
End of MIB

it miss lot of informations because with my windows i have more informations
thanks for your help.

ps: sorry for my english i'm french