for the life of me I can't see how to configure my buttons in Synapse 4, can anyone help?

I’m trying to program the buttons on my new Naga Pro. I’ve downloaded Synapse 4 from Razer and I’ve opened it and selected my device, but I am not seeing anyway to do this. I’m sure it’s something easy that I’ve missed. Could anyone please give me directions on how to do this? A simple explanation would be much appreciated!

Thanks!