Timing Simulation - (ModelSim)

HI.

Well this FAQ has been very kind to me and wish it to be the same for
all learners.
What my main prob is, i want to learn "TIMING SIMULATION". I'am
basically a Front end VErification engineer, i have no idea on Timing
Simulation. SUppose i have a simple design in VHDL. say a counter. i
have done the functionality simulation and now want to try out the
timing simualtion. i was told timing sim. is only for designers and not
for verification engineers. But i want to get some idea may never know
when it will be help full.

I just tried out the timing simulation run and i found out that i need
to add few libraries and few files. (guess the library files are for
ModelSim) i have no idea what i'am supposed to do or what files and
libraries i need to add in order to get the simulation. I'am using
Xilinx editor and ModelSim Simulation tool. could anyone out here plz
tell me, how to generate a file from modelsim after functionality
simulation and what kind of files to add.it will be really helpfull.

Thanks and lots.
CHEERS!!

Abs