Look for a good mp3 to wav converter, you can find free evaluation versions online that let you convert 30 files and then you have to buy the program, (or so they say...). Then you should wind up with a wav file of the mp3 that is 10+ mb. Now open up Sound Recorder, assuming you are running a Windows based OS. You can find this by going to Start--->Programs--->Accesories--->Entertainment (on Win ME)--->Sound Recorder. Open up your new wav file, it will take awhile to open since it is a large file, but once you get it open, play the file, and when you get to the portion of the file you want, stop the wav right before the section, and go to Edit--->Delete before Current Position. Click OK and that part you want should be the beginning of the file now. Next, play the file and stop right after the section you want to save is finished, and go to Edit--->Delete after current position. Click OK. Now your file should be just the section you want.
If you are still confused, let me know here, I'll give you my E-mail address, and you send me the mp3 and the part you want saved, and I'll do it for you.