For reference, please consult this website: http://audacity.sourceforge.net/manual-1.2/toolbar.html
It describes the tools very detailed.
This refers to the edit toolbar: http://audacity.sourceforge.net/manual-1.2/toolbar_edit.html
Helpful info on saving or exporting projects: http://audacity.sourceforge.net/manual-1.2/menu_file.html
1. Open the MP3 file: “File” --> “Import” --> “Audio” --> select the file you want to work with
2. Select the part of the audio that you want to be its own track by clicking the “selection tool” from the toolbar
3. “Edit” --> “Cut” selected part: This places it on the clipboard and removes it from the original file.
4. “Edit” --> “Split” selected part: Moves the selected part in its own track and is replaced with silence in the original file.
5. “File” and choose “Save project” --> for an unfinished project: Saves the current Audacity project (AUP) file. Audacity projects are not intended to be read by other programs, but they are extremely fast to load and save within Audacity.
(Note that most of the audio data for an Audacity project is not stored in the AUP file, but in a directory (folder) with the same name as the project. For example, if you save a project as chanson.aup, there will be a directory called chanson_data created to store the actual audio tracks of the project.)
Select “Save project as…” if you need to give it a different name or move it to a different location!
6. “File” and choose “Export program” --> for the finished project: If you need to use it in a different program, export it in the file format that is needed.
Update: We need to use export and change the format to wav.!!!