disable dhcp on you router?

Followed the discussion about "Suse 9.3 DNS server setup" and found in one of the possible solutions the sentence "1) disable dhcp on you router". For me my router is something that I hung at a wall, that is connected with the ADSL phone line and my computer. It works and as a matter of fact I do not know what it does. Is there some way to find out what the router does? If I could disable dhcp, how could I restore it. Where to find out more about the innards of routers. Google was not the solution to learn something about routers in my case.