If you are using a Mac, you may want to use the free GarageBand application to edit audio. GarageBand is a complete recording studio and allows you to record, arrange, and add external audio and effects.
If you are using a Mac, GarageBand is probably already on your computer. Find the application and open it. If you can't find it, go to the app store and type in GarageBand and you will have the option to download it.
Once you've opened the app, you'll be prompted to choose which type of project you want to start. If you are creating a podcast, you'll want to start with the Empty Project option. The Voice option adds effects that you may not want. If you are creating music, then you may want to select one of the Factory Templates to get started.
Choose which type of track you would like. For podcasts, choose the Record using a microphone or line input option. You can also choose the hear as you play option so you can listen while you record. Once you have made your selections, click Create.
When you start a new project, the project opens with a track ready for recording.
To record on your new track, simply press the red Record button. When you are done click stop.
GarageBand offers a count-in feature which counts four beats before recording actually starts. It also has a metronome to help you keep the beat. You can toggle these on and off by clicking on the icons at the top of the application.
To add additional tracks, select Track > New Track or ctrl+click on the track area and select New Audio Track. You can also select the Add Track button (+) above the track header.
To rename a track double-click on the track name or use ctrl+click on the track you would like to edit to open the track menu options.
Hold down an empty part of the track header and drag it to the new location. You can drag sections within a track or between tracks.
To import audio clips, open the library by selecting View > Show Media Browser.
You can also find files in Finder and simply drag and drop them over to the track area. Media files can be added to an existing track or added to a new track depending on where you decide to "drop" the file.
By selecting the Edit option you can split tracks, join tracks, and cut copy and paste.
To adjust the volume of a particular track, move the Volume slider left or right to lower or raise the volume.
Hovering over the bottom portion of a track will allow you to adjust the length of the track.
For mixing options select Mix > Automation to show the automation curve on the track. This will allow you to adjust volume for certain parts of the track. Other options such as panning and special effects like reverb and echo are also available from the Automation menu.
To export your creation, select the Share option from the menu and choose where you would like to send the file. You can send to iTunes, the Media Browser, or SoundCloud. You may also opt to save the audio to disk.
For detailed help on all of the options available within GarageBand, please consult the GarageBand help documentation.