This help topic describes the audio effects that can be applied to any audio clip. The effects are found by opening the Effect Chain dialog. You can open the effects chain dialog by right clicking an audio clip and selecting Track Effects... Alternatively you can also open the dialog by selecting an audio clip and clicking Audio -> Track Effects... in the top menu.
Some effects come with a series of options known as Presets. The idea behind presets is to save you having to fiddle around with the numbers, which is great if the numbers don't mean a lot to you. Instead, you can just browse the preset list and select the option which best describes the effect you are trying to achieve.