You just need to connect the positive and negative from the transmitter pack to the output of the charger - just like any race pack. If you'd bought a Core RC charger, you would have a lead to do this
However, that aside, i'm not actually convinced that is the right balance port/board either - the connectors don't look the same. There are 2 that are similar, and I think that is what you have - but i don't think they are the same.
As another aside - my LRP transmitter pack isn't keen on being charged any higher than 2A. Not sure if it's the pack or my core charger, bust it tends to do some random stuff if i try to charge higher. 2A and it's spot on.