Given the partial datasheet below (I do have the entire thing) I am unsure how to use these numbers to drive the mosfet.

I am sure that I am misunderstanding some basic concepts here and pardon my ignorance, but here are my assumptions..

Qg (total gate charge ) is 71nC at 10V. 
So if i divide 71nC by 10V i should get an equivalent capacitor at the gate. At least that is what I think. (and if this is wrong everything that follows consequently is also wrong) 

However further down the datasheet input capacitance is given at 1960 pF.

Why is that not equal to the value I calculated above..After all the gate is the input so given a certain charge and voltage i can calculate the equivalent capacitance.

Further more is states in a grpah that Ciss is Cgd + Cgs.... but when i calculate those capacitance from the given Qgs and Qgd the numbers are not even close.

My guess is that I am calculating those capacitance from the given charge completely wrong .

[![enter image description here](https://i.stack.imgur.com/X24e4.jpg)](https://i.stack.imgur.com/X24e4.jpg)

[![enter image description here](https://i.stack.imgur.com/PkDxp.jpg)](https://i.stack.imgur.com/PkDxp.jpg)

Furthermore the datasheet stats 71nC at Vgs 10V but this graph below does not come even close to representing that...
[![enter image description here](https://i.stack.imgur.com/HKujC.png)](https://i.stack.imgur.com/HKujC.png)