You choose an IP address from the range which is accepted by the router. Usually something between 192.168.1.100 to 192.168.1.250 is reserved for DHCP and addresses between 192.168.1.1 to 192.168.1.99 are free for static use. This should be configurable on the router.
Standard gateway ist the IP address of the router. To be more precise: the IP address of the computer on the other end of the cable connected to your Amiga.
Network mask is 255.255.255.0
DNS is either the IP address of your router (if it supports that) or the DNS address of your ISP.
These few things should be sufficient to go online.
Try to ping the router. Try to ping the PC. Try to ping
www.amiga.com. If the latter does not work, try it on the PC, remember the IP address and ping the IP address of
www.amiga.com. If this works, you gave an incorrect DNS address.
Bye,
Thomas