NLB quick setup

I have am setting up a 2 node cluster with ms nlb 2 nics in each server

1) have my advertised adress and name

2) when asked to connect to host I give it my primary nic address (not
heartbeat)

3) It binds then I click add host and give it the primary address of my
second server

3) i see no place to tell it which interface is my heartbeat ?

They use the phrase 'cluster interface' -- is this the heart beat or the
primary ?

ideas ?
TIA