How to open .WAV or .MP3?

Having trouble with LMMS? Ask about it here.
Ok, I have a .WAV file, a song, a complete dong. I want it to open on LMMS because I will use this song to continue a music I am making on LMMS.

I have put it on the "Samples" folder, then drag it on the baseline editor. However, it does not play. It seems I have to open it in the piano roll editor, then it will appear on the Song editor to play.

Can someone help me here? I want it to play directly, no need to play it in the piano-roll editor because it is a complete song. I am not making a tune from that song. Thank!
large soundfiles are meant to be played with the sample-track container.
Click in somaple-track in the songeditor. That will create a back container, then Just drag a wave-file from any folder open lmms, into the sample-track-contaier (default, thres one is in all project, but you can add one from the speed-bar)
MP3 is not supported!
Why exactly can'tyou add MP3 support? Malware audio players even have that.