So I have everything set up right, like my mic through the computer (in the pink mic hole thing) and recording onto Audacity, but when I have the source as microphone, I get nothing. When I change the source to Line In I get sound, but it's very very quiet. So I'm wondering what's up.

The Walking Dead
Thats what the amplify and normalize effects are for, recording through either your mic or the line in through audacity will always be quiet. Just boost it up.
Too much gain = Ears in pain