First, what model did you load? Second, did you try "AC Analysis?" If so, it will ask number of points, start frequency and end frequency. The defaults of 1000, 10 and 20000 are fine. Click "Run." Then you will be told to pick variables to plot. Choose v(1) voltage and v(6) voltage if you are running the π two-way crossover models. Also select "Magnitude" and "DB Scale" checkboxes.

A grid will appear. Select "Format - X Axis" and check the values shown. The defaults are fine, being Minimum 0, Maximum 20000, Increment 5000, and Minor Tics 4. I like to select the checkbox to "display grid." Click "OK." Now select "Format - Y Axis" and check the values. The defaults are no good on this one, enter Minimum -50, Maximum 0, Increment 10, Minor Tics 4 and check "display grid."

You can click the little button that looks like a traffic light and it will start the simulation and show the response graph. When one is running, you can click exit to stop it and allow you to play with the variables. If you want to change a value of a part - like those used for R1, R2 and C1 - just change the number in the corresponding value field of the model description file.

I hope that gets you going. After you start getting some graphs, you'll probably catch on very fast. Don't hesitate to write back as you find more stuff you want to do, or things you want to know. And please be sure to post if you find something interesting too!