Audacity is a sound recording and editing application for Linux, Windows and Macintosh platforms. It should be available via the Package Manager on your particular distro, but if not it can be downloaded from http://audacity.sourceforge.net. The package size is about 6Mb. Audacity is installed in the Sound & Video section of the Applications menu, and the first time it is opened it presents a help screen with hyperlinks to instructions for common tasks. This can be left to appear on startup or turned off as the user becomes more experienced. A full set of help files can be downloaded from the Audacity home site, with a user manual in both HTML or PDF formats. Setting up is done via Edit / Preferences, which allows the user to set an input and output device and to set the sampling quality of the recorded tracks, plus much more.
The Audacity screen is fairly simple, with a set of buttons at the upper left for Play, Pause, Stop, Fast Forward, Fast Reverse and Record, and a timeline showing the length of the track as a waveform or spectrum. This is shown in seconds by default, but once a track is loaded the user can zoom in and out at will. Zooming in to the highest magnification shows the individual sound samples as dots, which can then be manipulated individually with a Drawing tool. There is also a Timeshift tool for moving samples back and forward along the timeline, and an Envelope tool which allows the dynamics of a track to be adjusted visually.
Sounds can be recorded from a microphone or by line-in from another device. It should be possible to record sounds or music being played or produced by other programs, but I found that while RhythmBox was running Audacity could not find the sound devices, so an intermediary program may be required here.
Audacity working on two stereo tracks 