Nitrogen Cycle: Nitrogen Fixation, Assimilation, Ammonification, Denitrification?

[Kylash]

So I've got this assignment where I've laid out the Nitrogen Cycle and need to label each of the processes involved the cycle is:
Plant to Animal to Animal Waste to Soil to Ground Water to Surface Water to Ocean to Groundwater to Surface Water. That's how the nitrogen flows. I need to use the terms:
Nitrogen Fixation
Assimilation
Ammonification
Denitrification
to label each of the processes (for example from Plant to Animal).
I'm really struggling so some help would be greatly appreciated.

Thanks.