We are excited to announce that we have launched our new Hive Community! HiveNation will remain as an archive, but all new posts, discussions, and articles will be created on Hive Community. You can visit our new community at thehivecommunity.aerohive.com
In general, our Aerohive TechPubs team is absolutely phenomenal and includes information like this in the context-sensitive HiveManager Help. If you go to Configuration - Advanced - Common Objects - DHCP Server/Relay, and then click on the HiveManager Help button in the upper right of your screen, there are step-by-step instructions for setting this up.