Cisco IOS Steps
Configure the following on the interface you want to capture netflows on. Most cases you would enable on WAN and LAN
interface gig0/0/0
description WAN
ip nbar protocol-discovery
ip flow ingress
interface gig0/0/1
description LAN
ip nbar protocol-discovery
ip flow ingress
Now Configure your Flow Exporter
You will export to your netflow server via the LAN interface unless its cloud based.
ip flow-export source GigabitEthernet0/0/1
Change the IP address and the port destination
ip flow-export destination 192.168.1.5 9999
Cisco IOS XE is a lot different to configure NetFlow here are the steps
First let configure our netflow exporter
flow exporter netflow
destination 192.168.1.5
source GigabitEthernet0/0/1
transport udp 9999
export-protocol netflow-v5
Now Let configure the netflow Monitor
flow monitor netflow
exporter netflow
record netflow-original
Now configure your interfaces
Interface gig0/0/0
description WAN
ip flow monitor netflow input
ip nbar protocol-discovery
Interface gig0/0/1
description LAN
ip flow monitor netflow input
ip nbar protocol-discovery