I love to listen other people's recording in their profile. Both covers and original tunes. One of the problems that I run into a lot is that I can't hear your recording. I'm not sure why so many people do this. You would think that they would listen to their own recordings and realize that unless you crank your volume control and speakers there's nothing there!
Don't be a noob and post a tune that can't be heard. Compare the volume of your own recording against a commercial tune encoded to mp3. Then go and get yourself a copy of Audacity. It's free. Load your song into Audacity, select the whole track by clicking on the box to the left of the waveform, and then go to the menu "Effects". Select the "Normalize" function. The dialog will give you an option to Normalize to a DB level. Normalizing to -3DB should be fine.
You can then export the audio to a Wave file and use your own app to encode to an MP3. Or you can go get the Lame MP3 encoder DLL (also free) and the MP3 export will be enabled in Audacity.