I had to screw around with alsamixer and soundcard configuration to get audacity to record radio on my pc, so the following is for capture (you might need line in enabled in the soundcard if you want to record with a mic.)
I can tell you what I did, but it may not work in your case.
go into 'alsamixer', set the card to 'capture', Analog S = phone, Digital = IEC958o, Master/Phone/Iec958f/Analog* all turned up.
disable every other device/setting.
then I go into audacity preferences and set PLAYACK&RECORD to: ALSA:default.
it may or may not work with your soundcard, in which case your going to need to spend some time fiddling with options untill you get it right