HFSS-Gaussian beam (laser beam) how to ?? PLS HELP

Hi all,

I have such a problem. I deal with the spread of electromagnetic waves in space (air). Electromagnetic wave should have kept a laser beam with Gaussian distribution of intenzity field. But I'm a newbie in working with HFSS so I need advice on how to handle this task. I'm thinking about using GaussianBeam incident wave or Classic waveport, Please HELP me!! PLEASE THX.