Your question is a little confusing. If you have actual CD audio, then it won’t contain any MP3 files. Its a different format.
Its possible you’ve got a bunch of files burned as data on a CD, and those data files are actually MP3 audio, I’ll grant you that. But it isn’t a CD audio disc.
So what do you want? A real CD audio disc or a disc with assorted MP3 files?
If you want a real CD, use ImgBurn to make a CUE file from the assorted songs you want to put onto the CD. You do this by clicking Tools–>Create Cue File. Burn the CUE file to a disc with ImgBurn. If you can play the songs on the computer, then you have the necessary decoders installed, and ImgBurn can successfully handle them to make the CUE file.