How to make a new part or a new model?

Which tool you are referring here? Is it OrCAD Capture/Design Entry CIS or Design Entry HDL?

I am using Modeled.exe from the pspice folder. I want to put the new model into the Capture to finish the schemetic with other components. Now I have managed to make a new MOSFET model and also exported to the capture. But I still have two questions:

1)  It could generate the netlist well in capture but couldn't figure out any simulation result. The pspice said the model used is undefined. I have added the nom.lib as global according to other people's advice.  But still can't work.

2)When I use Modeled.exe, I found I have to build up a new model based on present model. I want to build up a new model according to some certain math function. say, non-linear power source. How can I do it?

I am not English speaker and my English is poor.  So hope you can understand and I would appreciate any help from you.

 Thanks a lot and have a nice day!

You need to include the model library in your simulation profile. Select Edit>Simulation profile from profile menu. In simulation setting dialog select the Configuration files TAB, select libraries in that TAB. Browse and add the library file which has the models.

This will enable PSpice to pick the models.

On your second question how to develop non linear sources: You need to write your own spice subckt for such models. Typically these are done using behavioral devices and expression. Model editor may not be able to provide a readymade model for that, however once you have developed your model you can use model editor to create schematic symbols for that.

You may want to refer following app note related to behavioral modeling

http://www.cadence.com/rl/Resources/application_notes/Analog_Behavioral_Modeling_appnote.pdf

http://www.cadence.com/rl/Resources/application_notes/nonlinear_capacitor_model_appnote.pdf