need your help urgently wifi

hi im new to this forum , i have a reliance broadnet service i also hve a beete 450tc1 adsl2+ router . how do i connect the the two . i have the cable coming in from the reliance distribution box to the black colored modem they give and from there i attached rj45 cable to the wan port on the wifi beetel but im unable to connect can some one plz give a step by step walkthrough. Thanks