Recording from 2 Devices?

I have skimmed through the posts and I havent found this exact question and or answer.  I need to make a pretty simple audio production.  I have a basic USB mic, nothing fancy.  I am able to record the mic fine into adobe, however I want to be able to play audio (say in itunes or VLC) pause it and comment on it.  I am having toruble getting that played audio to record into adobe.  Seems like I cant have 2 sources?  I would think one could do this without a mixed, but maybe im wrong.  I even thought about doing a "line in" from another PC and playing the audio from there, but I cant get the "line in" to record either. 

Is there a setting solution for this?  Thanks for taking the time to read this and share your knowledge!