It's not graphical in the way the Equalizer has sliding bands.
Select the Parametric Equalizer, and hit the Add button. A drop down menu will occur, and select the type of adjustment you want (like you read about in the article). For example, select Adjust a frequency.
When you do this, you will see a new entry appear in the filters box. Select it, and fill out the parameters that appear below. Editing them is live, so you can hear the sound change as you type in different values. For the equalizer filter, you must put in the frequency, the Q, the Gain (use negative for a cut) and the channels it applies to.
