Audacity is free, open source audio editing software for Windows, Mac and Linux.
Getting Started
Go to https://www.audacityteam.org/ to download the software.
Open the application once it is downloaded to start a new project.
Recording
Select a microphone
If you have an external microphone plugged in, make sure it is selected from the microphone dropdown option.

Record Audio
To record from your microphone select the record button.

To stop recording press the stop button. To listen to what you recorded, press play.
A track will automatically be created the first time you select record from within a new project.
Adding Tracks
To add additional tracks, select Tracks > Add New and pick if you want Mono, Stereo, etc.
Rearranging and Naming Tracks
To name the track or rearrange the order of the tracks, click on the down arrow next to the track name and choose the option from the dropdown menu.

Importing Audio
If you need to import external audio and music files select File > Import > Audio and select the file you would like to import. The audio will import as a new track in your project.

Editing Audio
You can use the icons at the top to perform a variety of tasks including cut, copy and paste. You can use these options to cut, copy and paste parts of tracks or entire sections.

If you need to move a track on the timeline, use the shift icon.

The selection icon also allows you to select a section of audio track, and perform different operations just on that section.

Other tools are available to make the perfect audio recording.
Exporting
To export, choose File > Export and select the type of audio file you would like.

For detailed help on all of the tools available and for additional support, please consult the Audacity Online Manual.