MP3s are a popular audio file format that play on just about any computer or digital music player. Millions of people download and trade previously existing MP3 files every day. However, you can record your own MP3 files with nothing more than a microphone and a free audio recording program. This is a great way to create podcasts, record notes or make a sound file for just about any purpose that you can think of.
Set up your microphone. To record sound, you will need some kind of device for capturing sound. Many computers now have internal microphones. However, if your computer does not have an internal microphone, you will need to buy an external one. Plug your external microphone into the input jack or USB port on your computer.
Download a free recording software like Audacity. Audacity is a free, open source program that comes highly recommended by CNET with a five star editors rating. There are others, but none with the reputation of Audacity. Go to the Audacity website, download the program (which works in OSX, Windows, and Linux), and install it on your hard drive.
Download the LAME MP3 encoder. To create MP3 files on Audacity, you will also need the LAME MP3 encoder. Download this at the LAME website, and install it to your hard drive.
Record your audio. Press the "record" button, which is represented by a red circle. Using either your external or internal microphone, record as much audio as you need. When you are done recording, press the "stop" button, which is represented by a yellow square.
Export the sound file as an MP3. When you are done recording your sound file, you must export it to MP3 format. Click the "File" drop down menu, and select "Export MP3 As." Then enter a file name for your sound file.
Enter ID3 tag information. After you have saved your file, the ID3 information window will pop up. This is the place for you to enter information like title, artist, year of release, album title, and track number. Enter in as much information as you can here, as it will make finding and sorting the program in your computer's MP3 player much easier.