Basic Newbie Question

Hi, apologies for the basic nature of my query, but I cannot find ANY information about this.

I have purchased an iTach Flex (IP) along with a tri-port cable.  This cable has 2 x IR Emitters and 1 x Blaster.

How do I position the cables? I want to use the Blaster, so I just position that in front of the devices somewhere? Does that also mean that I don't use the 2 x emitters?

If so, do I then set the Network tri flex port to blaster "true"?  along with single emitter "true".

Then, do my devices work on Port 1,2 or 3??

(Oh, I am trying to set this up with Roomie in the UK)

Any advice would be greatly appreciated

Thanks in advance,  Gary