Open your audio editing software and import your MP3 files. Click "File" and then select "Import Audio." Type the name of your MP3 file in the search bar. Click once on your MP3 file and then click the "OK" button. Repeat this process with each MP3 track you wish to import. Check your audio software's user manual for more specific steps on importing audio tracks.
Select the audio track you want first in your final MP3 file. The audio editing software will automatically create separate audio tracks for each MP3 file you import. Click on the track that you want to be the first track in your final file.
Move the audio playhead to the end of the selected track. The playhead looks like a long vertical line that moves from left to right when you play audio in the software program. Click and drag this line to the end of the first audio track you selected.
Copy and paste another MP3 audio track at the end of another MP3 track. Click the next audio track you want to play after the first file. Select "Edit" and then choose "Copy." Click the first track again. Select "Edit" and then click "Paste at Playhead." Your audio software may just have a "Paste" function. Choose this option as the results will be the same.
Repeat steps two through four for each additional mp3 file. The only change should be that you continue pasting each file onto the end of this audio chain.
Delete unneeded tracks and export your combined MP3 file. Click each track other than the one you want to export while holding the "Shift" button on your computer. Press the "Delete" button to remove these tracks. Select "File" and then choose "Export Audio." Type a name for your file in the new window. Click the "Export" button to start exporting your new MP3 file. Check the user manual of your audio editing software for more specific instructions on exporting audio.