I am using version 2.0.3 on a Windows 8 OS.
How can I go in to a track delete just a portion and re-record that section without having to create another track.
The only way I know of to record twice on the same track is Append Record (Shift-R) and that only works at the end of the show.
You can set up for Overdubbing, record the new segment at the right time and then produce the appropriate ins and outs by fading or careful cutting. If it’s a significant portion of the show, you may find that getting into the correction is simple, but getting out without damaging the rest of the show isn’t.
http://manual.audacityteam.org/o/man/tutorial_recording_multi_track_overdubs.html
Koz
There is also a crude work around if you are adamant you want to record on the same track, replacing something in the middle of the track, and you have adequate silence either side of what you want to replace.
Select what you want to delete, Edit > Find Zero Crossings. Delete that selection. Select from the delete point to the end of the track, Edit > Cut. Append Record (SHIFT + R or hold SHIFT and click Record). SHIFT + A to Stop and Set Cursor. Edit > Paste.
Gale