#1
I use a evh 5153 head if that matters. But i have a home pc and planned on downloading audacity. Id like to record my black dahlia/ as i lay dying covers but im getting mixed answers on what to use as far as equipment. Some say line 6 pod another said miking the stereo and another said a plug in adapter to go into head phone jack on computer. Anyway i need to plug headphones in as well to hear song im covering.
#2
regardless of what you do, I'd suggest Reaper instead of Audacity.  It'll be much easier to work with.

As far as equipment goes, I'd suggest a USB soundcard (like the Focusrite scarlett) with some amp sims

What do you mean "miking the stereo"?
#4
It would help to know budget? Are you just recording guitar or vocals as well? What recording quality you are looking for? Is this just some quick work or will you possibly be more extensive recording later? 
Audacity will work but has limitations as a real DAW. Reaper as already mentioned would be a better choice. Or if you should purchase an interface, it will come with a DAW, although personally I still prefer Reaper. 
Should mention, do not plug a microphone or anything but a headphone into your computer's headphone jack! headphone jack is output, not input. Maybe you or your friend meant mic input on your computer. 

At a minimum for most people I would recommend a small interface like Focusrite, Alesis, Steinberg or even Behringer has a $50 one. 
Audacity will l work but is not great. Also while it supports plugins like VST's  which there are many free for reverb, effects, amp sims. DAW's like Reaper (and Cubase & others) support VST instruments (drums, piano, etc.) which can be very useful and Audacity does not support last time I checked VST instruments.