Adding to Tracks Already Present

How do I go to the end of what I already have and add another verse? That would include all the tracks with instruments.
Also, is there any information out there to show how to take out a bad part of a track, and replace it with something better?

SHIFT-click on the record button to append-record to the selected track(s). I’m not sure what you mean by “all the tracks and instruments” - Audacity can only simultaneously record as many tracks as your hardware supports.

Append-record is not the best way to make a seamless addition to previously-recorded material. Better is to click in the previously-recorded track a few seconds before the end (so you’ve got some idea of where to come in), then click the Record button - a new track will be created and recording will begin at the cursor position. Make sure you have Overdub turned on so you can hear the previously-recorded track(s). Once you have the new recording you can cut-and-paste to tack the new part on the end of the old part. Or you may want to cross-fade the old and new parts for a more seamless transition - this will require maintaining the two separate tracks, creating the cross-fades, listening until you get them right, then doing a Mix and Render with those two tracks selected which will mix them to one track, thus making the cross-fade permanent.

This is sometimes called “punch-in recording” - try a google search for that phrase.

Use a similar technique to the one described above. Select the bad part of the track and click on Edit > Silence Audio - now the bad part is gone. Click a few seconds before the bad part and click record - recording will begin on a new track at the cursor position. Listen to the old track and begin playing along, playing through and past the silent part of the old track. Now you can either cut-and-paste the new part into the old track, or do a cross-fade between them.

The best way to learn this is to experiment on something non-critical. Create a project just for learning, and use that to try out different techniques. This is not a skill you are going to learn in 5 minutes, but maybe in 5 hours if you approach it in a disciplined, logical fashion. Keep it simple - just one track with a mistake you want to correct.

– Bill