When it comes time for you Jam Incubator jammers to submit your mp3's (no hurry - take as much time as you like to practice and record), here is what we need. Please look at Step 3b carefully, that seems to be where the confusion is happening.
[These are the instructions given to me (Thanks, Dan T!) when I participated in a jam. They worked great.]
Open Audacity.
1) Import the backing track (BT) into Audacity by selecting "Project - Import Audio"
2) Recording your part -- Click on the actual track, several seconds before your designated segment begins (this will put a little line on the track, and when you hit "Record" or "Play" the track will start from that point where the line is, and you'll have a few seconds lead-in to get ready to jam.)
You can then record your part, and click "Stop" after you've finished your part.
Listen to your part--if you don't like it - go to "Edit - Undo Record", and then try again. If you are happy with your part and want to save it, go to Step 3.
3)
a) Saving entire BT with your part -- Go to "Edit - Preferences" [NOTE: on some versions of Audacity, it is "File - Preferences"] click "Quality" tab - make sure this setting is at 44100Hz & 32-bit, then click "File Formats" tab - set bit rate to 64. Click "OK". Go to "File - Export as MP3" - and save it to your documents or desktop (make sure you know where you saved it to).
b) THIS IS THE MOST IMPORTANT PART, AS THIS IS WHAT WILL END UP IN THE MIX: Saving just your part, with just a bit of the beginning of the BT for easy editing: Go to "Edit - Preferences" [NOTE: on some versions of Audacity, it is "File - Preferences"] - click "Quality" tab - make sure this setting is at 44100Hz and 32-bit, then click "File Formats" tab - set bit rate to 128 (note this is diff than in step 3a). Click "OK".
Click and hold on the very beginning of the BT, and drag to the right just a little and then let go. Click "Play" (you should hear just the very beginning of the BT, and then it stops.) Go to - "Edit - Trim" - the entire BT should be erased except for the little bit that you selected at the beginning, and your part is the only other thing left. Go to "File - Export as MP3" - and save it to your documents or desktop (make sure you know where you saved it to).
4) Send two separate emails to the host (Margaret's note--my email address will be provided to participants by PM--let me know when you are ready for the addy), with one mp3 of each of your parts saved above attached. (Two separate emails to make sure the attachments aren't too big to pass through).
If you have any questions or problems with this, post your questions on this thread and we'll call in the Big Dogs.

Good Luck and Happy Jamming!
Margaret