OS 10.8.4 - Audacity 2.0.3. dmg installer. This is my first lp recording and upon playing it back in Audacity I hear both sides at the same time. How to play one side at a time? Thanks!
If you pressed Record twice, once for side A and once for side B, then Audacity would have piled two stereo tracks one on top of the other and they will both play at once. You can select one or the other with the SOLO and MUTE buttons to the left of each track.
Creating MP3s and chopping up the songs is covered in a wiki.
This is the advice from the Audacity Manual:
Start your recording by pressing the red Record button from the Transport Toolbar, then starting the player. You can pause and restart the recording between tracks or sides with the blue Pause button, which keeps your recording on one track within Audacity. This is the easiest way to record into Audacity, because having just one track on screen allows you to split the recording up into the different songs or sections using “labels”. See the tutorial: Splitting a recording into separate tracks for more on this.
An alternative to using the Pause button is to Stop the recording at the end of the first side, then use Transport > Append Record (or shift-click on the Record button, or use the keyboard shortcut SHIFT+R) to continue recording on the existing track.
It comes from a set of tutorials that is likely to be useful to you: Tutorial - Copying tapes, LPs or minidiscs to CD