Hello,
Then use an Ethernet cable to connect one of your router's LAN ports to your Time Capsule's WAN port. After a moment or two, your router will assign the Time Capsule its own IP address and the Time Capsule's hard drive should appear as a Time Machine candidate on any Mac connected to the same network.
Thanks.
For More go to:-
Apple Router Setup
Apple Time Capsule Setup
Time Capsule Setup