Go to https://www.audacityteam.org/download/. Per your operating system, click the corresponding download link and follow the relevant installation instructions. Windows users will be given the option to download the software as an .exe installer or a ZIP archive; the former is preferable for easy installation.

By this point, you should have the latest version of Audacity installed on your computer. Opening the program, your window should look something like the image below, minus my marks.

Audacity has additional toolbars that can turned on under “View”. There’s more information about them here. But these are the default ones and the ones you’re most likely to need:

1. Transport Toolbar: Controls both playback and recording. Click the red circle to start recording audio, and the black square to stop. 
2. Tools Toolbar: Contains the selection tool, the envelope tool which allows you to make smooth adjustments to the volume at different points on the track, the draw tool which you can use to redraw waveforms (advanced), and the multi-tool which allows you to switch between the other tools in the toolbar as well as zoom in and out by right-clicking. 
3. Edit Toolbar: Contains zoom-in and zoom-out, zoom-to selection, fit-to-width (which fits the entire track to the width of the screen), and a zoom toggle tool. There’s also trim audio, which removes all audio except for what's selected, silence audio which does the inverse, and the undo and redo buttons. 
4. Audio Setup Toolbar: This allows you to set up how audio will be recorded and played back. This is where you would select which microphone you’re recording on. 
5. Recording Meter Toolbar: Click Start Monitoring before recording, watch the bars and if they start to turn red, you’re audio is too loud and at risk for clipping (the same is true for the Playback Meter Toolbar to the right of it). 

Audacity, like most other audio (and video) editing platforms, is organized around “tracks,” which represent layers of sound. If you were producing a song in Audacity, you might have separate tracks for each instrument: one for the drum kit, another for guitar, vocals, etc. To add a new track, drag an audio file of any format into the dark blue space.

You can also record new audio tracks in Audacity, just make sure to select your recording device under File>Preferences or the Audio Setup Toolbar. If you are using multiple microphones, Audacity will automatically create a separate track for each one. 

Let’s say you’re editing a podcast, and want to cut together a series of tracks recorded at various times into a single, seamless montage. This might involve (a) trimming unimportant bits from each track, (b) cutting a track into multiple pieces, and moving each piece around, and (c) arranging each track so that one follows right after the other.

(a) First, trimming: click on the selection tool (in the Tools Toolbar). With your cursor, left-click and drag over the area on your track you’d like to remove. Upon doing this, the area you selected should be highlighted in white. If you’d like to modify the area you have selected, mouse over either edge of your selection until your cursor becomes a hand pointing left or right; drag the selection to your preference. To remove the area you have selected, press delete. (for Windows users, backspace also works) Your selection should now have disappeared. 

(b) As with (a), use the selector tool to specify which area of your track you’d like to excise and move around. However, once selected, press either command + x (MacOS) or ctrl + x (Windows) instead of delete. Then click on the dark blue workspace, or an open area of the current track where you’d like the clip to be, and press command/ctrl + v.

To move the clip, click and hold on the gray part at the top of the clip and drag it about the workspace to your preference. If you would like to move all of the clips you have in a given track, hold shift. 

(c) Click and hold the top of the track and drag it such that its start butts up against another track’s end (or its end against the other track’s start). You’ll notice that a yellow line will appear once the tracks become sufficiently close, and the two tracks will lock into a precise, sequential position; this indicates that one track will play immediately after the other. 

Let’s try editing a track such that it crescendos at its start and decrescendos at its end. Click on the envelope tool. Purple bars should appear above and below each track.

Like many other audio editing softwares, increases or decreases in volume in Audacity are represented graphically by “nodes.” Think of each node like points on a line graph: if one node “spikes” above or below its neighbor, this indicates a rapid increase or decrease in volume. On the other hand, one node gradually sloping into another indicates a slow increase or decrease in volume.

To create a new node, click on a track. You’ll see a white dot appears where you click: this a node. 

Then, click on another point later on in your track. Another node will appear. To create a crescendo between the first and the second nodes, drag the second node up. To create a decrescendo between the first and second nodes, drag the second node down.