what is Timing generating before interfacing?

Hi

'm having ADC chip "ADS 8364"  wit 25m Hz input Clock . ADC output Signal
Going to FPGA and its out signal going to processor fr further process.

my problem is before writing vhdl Code i want generate timings ADC to FPGA
but

(1) i don no what is this timing generation ? 

(2) why this necessary before Code ?

(3)Can any one give example timing code generation for ADC's

Waiting for all yur Inputs 

Joshi