How do effects work in Audacity ?

1. Select some audio

Use the mouse or keyboard shortcuts to select some audio. You can prelisten listen to that selection as many times as you like and adjust the boundaries of the selection.

2. Select an effect

You can pick any of the internal effects or a VST plugin(Windows & Mac). LADSPA(Linux) support is available in the 1.1 beta, but it's beta so be extra careful.

3. Tweak the parameters to your liking

Play around, go wild, honk your horn. Make those tough decisions without telling anyone why.

4. Let the software work

Hit the OK button. Or hit the Cancel button if you're unsure about something, like what time you were supposed to take the pizza out of the oven.

5. Not happy ? UNDO

That effect didn't cut it ? Did that delay show up too late and you wondered where the summer went ? No problem.

Hit UNDO in the Edit menu (or press CTRL+Z).

Then go back to 3. In fact you can hit undo so many times, YOU might disappear. Or perhaps just all your edits. Who knows.