CST Problem-Plane wave excitation

Dear All,
I have a problem with the excitation of a plane wave in CST 2010. I used quick start guide and reached the step 'Set Excitation' and I added a 'New Plane Wave'. This wave has the direction (0,0,-1) but looks like this is not all...there is still a missing step which should be done to set the excitation...I searched in help but no example for this process is found.
Thanks

May be I was not clear enough in last post...The problem is that I need to get RCS of a half space dielectric and I need to excite it by a plane wave normally incident...HFSS was not good in doing that so I decided to do that on CST 2010...Now can someone tell me the steps to do it on CST 2010?

It is fairly straight forward with CST. After defining frequency range and boundary conditions, the only thing is to define a plane wave. Go to Solve tab, choose a plane wave and choose the propagation direction e.g. X = -1 will launch the plane wave in -X direction. Also define the polarization of the wave. Once done, you need to define the field monitios for the desired frequency values. Choose Farfield/RCS.
I hope this will give you the results you are looking for.
Regards

Actually the problem is that I am using a frequency domain analysis with the quick start guide so when I reach the step set excitation and I define the plane wave with the desired polarization...after that the cursor doesn't move it seems like there is a missing step with which 'Set excitation' process finishes...I don't know what this step should be...after finishing 'Set excitation' process I should define the field monitor and boundary conditions

There is just a small point...I asked some people and they told me that you need to add a port 'discrete or waveguide' I think I don't need to add these ports as I need to get RCS from this slab not S11...What do you think?Can this be the problem?