I downloaded audacity but I don’t have the effects. I have no idea how to instal the Nyquist effects. Please help!
Have a look in the Effect menu. Do you have “Low Pass Filter” and “High Pass Filter” listed? (they should be below the dividing line in the Effect menu). If not, then Audacity is not installed correctly. To install Audacity correctly, first remove it from your computer (best to just start this again). then download Audacity from here http://audacityteam.org/download/mac and carefully follow the installation instructions.
Once you have that working, if you want to install additional Nyquist effects, see here: http://wiki.audacityteam.org/wiki/Download_Nyquist_Plug-ins#Installing_Plug-ins