Just trying the game. So nectar is reset every week?
edit: Dont understand exactly how the attack works. I guess the more cells the merrier?
The prizes are based on the increase over the week of Nectar. You can spend Nectar at any point by buying black chips (which adds defences to your army) or by buying and designing a new Sector which can be done here
http://growhive.io/?d=wuoFnggcT2z62owG&m=100,100 once you have enough Nectar accumulated.
Various cells are worth more than others - this is coded randomly (I don't even know which ones are worth more). The more cells, or territory you have, the merrier. This will then translate into Nectar over a few seconds.