Here's a short guide to get you started using Audacity, a piece of free software used for recording and processing audio.
Audacity can be downloaded from the official website.
As of now, 1.2.4b is the latest stable release of the software
and 1.3.0b is a beta version available for experimentation.
After you install Audacity, you will also want to install the LAME encoder as well. This will enable you to export your audio as .mp3 files, which has become a de-facto standard for audio among the AVA community. The latest LAME encoder can be found at this website.
I am currently using the "LAME MP3 Encoder 3.96 Final" version that has worked flawlessly for me so far. You'll want to download this file, and unzip the lame_enc.dll file into your Audacity program folder. (probably C:\Program Files\Audacity 1.2.4 if you used the default install settings.)
After this, run Audacity, and select "Edit->Preferences", click on the "File Formats" tab, and Press the "Find Library" button in the MP3 Export Setup box. Now select the directory where you unzipped the lame_enc.dll file into, and select the lame_enc.dll file. Now you are ready to start recording!
Make sure your microphone is plugged in, and press the red circle (record button) and record something. Press the yellow square to
stop recording. Press the green triangle button to play back the audio.
If you want to play back only a portion of the audio, select the portion of the audio in the "Audio Track" window you want to play by clicking and dragging using the left mouse button. Editing the audio in audacity is just like editing text. You can Cut, Copy, Paste and Delete the selected audio using Ctrl-X, Ctrl-C, Ctrl-V, and Delete respectively. Subsequent recordings generate new audio track windows. Note you can cut and paste audio from one window to the next. Also, Undo and Redo are available as well by using Ctrl-Z and Ctrl-Y respectively.
You can close the "Audio Track" subwindows not currently in use by clicking the [X] in the upper left corner of the subwindow.
The magnifying glass can be used to zoom into, and out of sections of the audio in case you want to manually remove any small pops or other nuances in your audio.
Chances are, your recording will be a bit staticky and will require a little cleaning up. Audacity provides a feature to do this as well called Noise Removal. Noise Removal is a two-step process.
First make a roughly three second recording of silence using your microphone (e.g. record and don't say anything). This will be used as an example for Audacity to learn the noise characteristics of your microphone as well as the ambient sounds of your surroundings. Next select the entire audio track, then choose "Effect->Noise Removal.." and press the "Get Noise Profile" Button. Now you can delete your recording of silence, since Audacity is finished recording it, and it won't be needed anymore.
Note that this process needs to be repeated every time you re-start Audacity.
Now you are ready to remove noise from actual audio clips. When you record you audio clips, it's a good idea to wait half a second before speaking and after speaking in order to provide some buffer space when working with the audio. Now record yourself speaking.
After this, highlight the entire audio clip, and select Effect->Noise Removal. Usually the noise removal amount slider is set to a good value, but you can test how different values sound by playing with the slider and using the "Preview" button. After you have found the best value, you can press the "OK" button to commit the results.
Usually this works well, but in some cases there may be a small pop near the end of your sample. Look (or listen for) for a small spike in the near the end of the audio track. Highlight it and delete it.
This is one of the reasons to record a little silence at the start and end of your samples.
The next step you will want to do is to run volume normalization on your audio. This will help to make your audio more consistent in volume with other people's audio clips, and will also help to remove any initial and final pops in your audio.
Highlight the audio track, and select "Effect->Normalization". Select both the "Remove DC Offset" and "Normalize Maximum Amplitude to -3dB"
If any portions of you audio are too soft or too loud after this, you can always highlight those portions, and adjust their volume using the "Effect->Amplify" option.
You will probably want to add echoes or other special effects to your audio at some point in the future. Here are some features of Audacity that I'm sure you will find very useful.
"Effect->Change Pitch": Some people have a really incredible vocal range, but for those of us who don't, or those of us who feel like working outside our range, there's the change pitch feature. The wonderful thing about Audacity's implementation of the feature is that it changes the pitch without changing the speed of the audio. Again, this feature only alters the selected portion of the audio.
"Effect->Echo": Adds echos to your samples. Set the delay to a low value (0.05) if you feel like talking like a transformer. Set the delay to a higher value if you want to announce a Monster Truck Rally. Decay determines how slowly the echoes fade out. Sometimes this feature can be very slow to compute. Another alternative is to use the "Effect->Delay" feature, which also produces echoes, but allows you to specify a maximum number of echoes to speed up the processing. Myself, I always use "Effect->Delay" feature for echoes.
"Effect->FFT Filter": Fast Fourier Transform filter, this is effectively a graphic equalizer for your sample that allows you to attenuate and amplify different sound frequencies in your audio. Think of it as fine tuned bass and treble adjustments. Click on the blue line to data points. Then drag the data points up and down to specify the amplitude adjustments for those portions of the spectrum. This feature can be useful for making a voice sound more distant or close, and can also be used to make it sound like the voice is over being spoken over the radio.
"Effect->Fade In/Out": This can be used to remove any initial pops at the beginning and end of your audio. It can also be useful to manually remove any small pops in your audio, but fading out a tiny section of audio up to and into pop, and fading back in after the pop.
At this point, you will probably learn more by experimenting with the settings than anything else. Good luck, and have fun!