use cli
example for inside network 15....
conf term
no dhcpd enable inside
no dhcpd address 192.168.1.2-192.168.1.129 inside
interface vlan1 ip address 192.168.15.1 255.255.255.0
dhcpd address 192.168.15.116-192.168.15.132 inside
dhcpd enable inside
wr mem