The MP3 format stands for Motion Picture Experts Group Layer 3, a digital compression algorithm that results in an audio file being 10 times smaller than the original raw file. MP3 technology has revolutionized the past decade, because everyone listens to music. Today, the MP3 format is one of the most popular in the world for playing music. It's pretty easy to learn how to create an MP3 file from scratch.
Steps

Step 1. Download and install [https://audacity.sourceforge.net Audacity], an open source audio editing program
This program will be useful when converting raw audio source file to MP3 format.

Step 2. Locate the microphone input on your computer
Most laptops have a built-in microphone, so just read the manual to find it. But, it is unlikely that desktop computers have a built-in microphone.
You can buy an inexpensive computer microphone from any electronics store. A cheap microphone will not produce high quality sound, but it will be sufficient for most users

Step 3. Launch Sound Recorder software
Windows has a default program that can record sound from a microphone. Go to Start -> Programs -> Accessories -> Entertainment -> Sound Recorder.

Step 4. Make a recording
Press the red button to record sound into Sound Recorder and speak into the microphone. When you are happy with the result, save the recording in WAV format.

Step 5. Launch the Audacity program
Select the Import option using the MP3 encoder. Click on the "Settings" menu and select "Custom". Set the MP3 encoding parameters according to your preference.

Step 6. Start the process of converting from WAV to MP3
Find the WAV audio file that you previously recorded. Go to File -> Export and save the file in MP3 format.

Step 7. Wait for the conversion process to complete
The MP3 encoder converts the original WAV file to an MP3 file of the same name. Do not interrupt the conversion process, otherwise you will have to start all over again.

Step 8. Enjoy your MP3 file
After you have completed the MP3 conversion process, you can download the resulting file on the internet or transfer it to your MP3 player or play it on your computer.