building a structure with hfss

I want to build a structure of coaxial resonator (RG-401/U) using HFSS to see the fields around it. Please can anybody help me cos I am new to HFSS?

What sort of help do you want? Define the frequency and according to it find the dimensions of your resonator, radius of the cylinders and lengths, then design it in HFSS and simulate it with eigenmode solver.For each mode that you are interested in you can plot the fields