en
conf t

int fa0/0
 ip add<press tab key> 192.168.1.1 255.255.255.0
 no shut
exit

int fa0/1
 ip add<press tab key> 192.168.2.1 255.255.255.0
 no shut
exit

int fa1/0
 ip add<press tab key> 192.168.3.1 255.255.255.0
 no shut
exit

exit

From enable mode -> show ip int bri (or) show ip interface brief
From enable mode -> show ip route