You should be able to give him whatever ip google tells you. For port forwarding internal and external ips should be 25565. Theres another number you would have to show me a picture of your router config for me to know the name but it may or may not be obvious, it should be the internal ip of your computer which you can find by opening terminal and typing "ifconfig" (yes ifconfig not ipconfig and without the quotation marks) then pressing enter and it will return a ton of random information something like this.
Your-Computer-Name:~ Username$ ifconfig
lo0: flags=8049<UP,LOOPBACK,RUNNING,MULTICAST> mtu 16384
options=3<RXCSUM,TXCSUM>
inet6 fe80::1%lo0 prefixlen 64 scopeid 0x1
inet 127.0.0.1 netmask 0xff000000
inet6 ::1 prefixlen 128
gif0: flags=8010<POINTOPOINT,MULTICAST> mtu 1280
stf0: flags=0<> mtu 1280
en0: flags=8863<UP,BROADCAST,SMART,RUNNING,SIMPLEX,MULTICAST> mtu 1500
options=2b<RXCSUM,TXCSUM,VLAN_HWTAGGING,TSO4>
ether 3c:07:54:2f:80:c4
media: autoselect (none)
status: inactive
en1: flags=8863<UP,BROADCAST,SMART,RUNNING,SIMPLEX,MULTICAST> mtu 1500
ether e4:ce:8f:67:a5:fb
inet6 fe80::e6ce:8fff:fe67:a5fb%en1 prefixlen 64 scopeid 0x5
inet 10.0.1.7 netmask 0xffffff00 broadcast 10.0.1.255
media: autoselect
status: active
p2p0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 2304
ether 06:ce:8f:67:a5:fb
media: autoselect
status: active
fw0: flags=8863<UP,BROADCAST,SMART,RUNNING,SIMPLEX,MULTICAST> mtu 4078
lladdr a4:b1:97:ff:fe:69:97:f0
media: autoselect <full-duplex>
status: inactive
You need the bolded and underlined number above it will probably be either a 192.168.x.x or 10.0.x.x number depending on how your router is setup. You should also be able to access your server within your network with this ip.