Modelling co-axial feed in HFSS

I want to model a co-axial feed to a microstrip antenna in HFSS 9.Can anyone help me as to how to go about doing it ? Thanks a lot.

First of all - you will find several topics on the board. Use the search function!

But to give you a short guidance:
Draw 3 cylinders (inner conductor, dielectric & outer conductor) with the correct dimensions and assign the appropriate materials. With this approach, you should be able to draw a model for a coaxial feedline.