All Right Now by FREE is just guitar and vocals (and drums) until the first chorus. Koss really carries it.
You need an interface that will record electric guitar and microphone. Maybe run the guitar through a boost. Just have at it and see what you get. Try it with a click track. Try it with a drum loop. Try it with no click or drum track. Add a little compression and reverb. Add an amp sim unless you're micing an amp, then you'll need two mic inputs.
Record it for the feel then if you don't like it use Direct Monitoring on your interface and do another guitar track or three. another vocal or three or how ever many of each. Keep the original, then choose what you like.
If you get a raw track you like and just can't make it sound the way you want, there are people here who are very good and many who will, I'm sure, help you out. You can record and ask someone to help you if you aren't happy... but just try. I know very well that it is hard when you don't know what you're doing. Lots of people here have been engineering, producing, recording for decades. When you just have a song idea, a guitar, and a voice.. it can be very intimidating and you can easily get completely lost in the technology.
So... just do what you can and if you don't like it, ask for help. You can post what you have on the Songs forum but be clear that you don't claim to be a producer, you're just trying to record a song and people will help you. If you aren't comfortable with that, listen to some of the songs on the Songs Forum. Pick a couple you identify with, and people you think you'd be comfortable talking to and ask if you can get help and share via dropbox or Soundcloud.
I know how you feel.. but just do it. If you're like me, you'll record your voice and think... ugh, do I really sound like that? but what your ears hear when you sing is different from what you hear recorded, through phones or speakers. It doesn't make it bad just different.
It's the only way,
just start. You can get direction once you are moving, no one can give direction to someone who isn't moving. (I mean that in a good way)!
You're trying to make a "Scratch Track". Just try it several different ways.... it don't have to sound good unless you're pitching it to a pro artist or something. If that is your intent, do the scratch track and get someone, some good musicians to record it. Plenty of people here to do that.
Rich Mullins' last album was released as a double CD. He died a week after doing the "demos" or "scratch tracks". He recorded them on a cheap cassette machine in an abandoned church, playing a piano and singing by himself. The playing and singing isn't so good but what his band and others did with them is incredible. It was called The Jesus Record. It is very interesting to hear him doing the scratch tracks then listen to the studio polished result. You can do this.
Willie Nelson wrote Crazy and pitched it to Patsy Cline's husband. Patsy didn't like it because Willie sort of spoke the words but.. from Wikipedia:
According to the Ellis Nassour biography Patsy Cline, Nelson, who at that time was known as a struggling songwriter by the name of Hugh Nelson, was a regular at Tootsie's Orchid Lounge on Nashville's Music Row, where he frequented with friends Kris Kristofferson and Roger Miller, both unknown songwriters at that time. Nelson met Cline's husband, Charlie Dick, at the bar one evening and pitched the song to him. Dick took the track home and played it for Cline, who absolutely hated it at first because Nelson's demo "spoke" the lyrics ahead of and behind the beat, about which an annoyed Cline remarked that she "couldn't sing like that".However, Cline's producer, Owen Bradley, loved the song and arranged it in the ballad form in which it was later recorded. On Loretta Lynn's album I Remember Patsy, Bradley reported that as Cline was still recovering from a recent automobile accident that nearly took her life, she'd had difficulty reaching the high notes of the song on the original production night due to her broken ribs. So after about four hours of trying – in the days of four songs being recorded in three hours – they called it a night. A week later she came back and recorded the lead vocal in one take. So... go for it! Lots of things happen when people just try. Do it.
Good luck! You'll do fine!
Julien