Hi,
I think what the rest meant is that you should first design in software using ADS design guide.
1. enter the centre freq, lower and upper pass-bands, attenuation etc
2. the "passive circuit" design guide will synthesize the required component values (either width and length of MLs or the RLC values for lumped components).
3. run simulation to see if the freq response is ok. Tune parameters or "optimize" if freq resp is not ok
4. click on "generate layout" to obtain a PCB mask
5. fabricate your hardware using the mask...
The difference between simulation result and actual hardware measure may vary, depending on many factors (eg ppm,Er over greq range, soldering, parasitics). You'll only know after you fabricate and test the 1st prototype i guess.
Hope I answered you question