DHCP on a Cisco 2620 Router

I have a client with a semi-outdated Cisco 2620 Router. I recently had to blow the whole thing out an reload from the original flash image. I don’t work with these things much and ciscos site is very un-helpful in this case. I need to setup the DHCP server inside the router, can anybody help me, all I need are the first initial commands and then I can hack it from there.
Thank You!