Tim, this is only a general overview, but it may help get you started.
First, you go to "project", then "import audio", and "grab" the audio you want (backing track, drum loop, whatever). This creates a new track in the view.
Audacity has a drop down menu, "effect", one of the effects is "repeat".
You can put your drum loop on a track, then use "repeat" to lengthen it to a useable length, EG, a 10 second loop can be made 3, or 5 min, or whatever.
You can make the drum, say, 2 mins. long, the make a new track w/ different drumbeat another 2 mins, in this way you change the drum and have a 4 min. song to work with.
You can then add 1 new track at a time, recording your bass, then guitar, etc., until you have a complete song.
By adding a new track for each instrument, you can adjust the volume of each one independently, and add effects, (reverb, etc.), to them as you go.
This way, you can also erase a track you're not satisfied with and save the others for another take.
As you "build" your song one track at a time, try to record each one at a level where you don't "peg" the meter at the top of the window. You want to record as loud as you can without driving the meter into the red, at 0 dbs.
Another effect is "normalize" in the same drop down menu "effect". This will help keep the volumes of each track even, but it won't "fix" a track recorded too hot that has excessive distortion or hiss.
So, I would suggest....
1. "Import Audio", grab the drum loop you want. "Repeat" , make it as long as you need.
2. "Record" , another track to add to the drum. Bass is a good second track to add.
3. "Record" , another tr. , say, rhythm guitar.
4. "Record , a lead guitar, another rhythm, etc.
Remember to monitor your levels as you add each track, try to keep them clean, with no distortion. Adjust the volumes of each track as you go so the mix sounds good to you, so the drums, bass, etc, don't drown out the other instruments.
You will have several tracks open on the screen at once, and any that you want to scratch you can simply close, and record that part over again. You can also use "mute" to silence that track only, or "solo" to listen to that track only.
Hope this helps, and maybe one of the "expert players" you mentioned will chime in later.
Guitars
Wilburn Versatare, '52 FrankenTele(Fender licensed parts), Fender USA Roadhouse Strat, Fender USA Standard B-bender Telecaster, Agile AL 3000 w/ WCR pickups, Ibanez MIJ V300 Acoustic, Squier Precision Bass,
Amps
Ceriatone Overtone Special, Musicman 212 Sixty-Five, Fender Blues Jr., Peavey Classic 30, Fender Super Reverb, Traynor YCV-40 WR Anniversary w/ matching 1x12 ext. cab, Epiphone SoCal 50w head w/ matching 4x12 cab (Lady Luck speakers), Avatar 2x12 semi-open back cab w/ Celestion speakers
Pedals
Digitech Bad Monkey, Digitech Jamman, DVM's ZYS, Goodrich volume pedal