Backing tracks are fine both for fun and practising at home as they are often the same as a professional DJ might use. When transferring your downloaded tracks to your computer hard drive and then to removable media (e.g. SD card) make sure that there are no punctuation marks such as "&" in the file name wording. Use only letters and numbers - otherwise the CDG file may not respond in the player - meaning that you may get music but no words on the screen. Remember that when you sing in public, the DJ may use a track from another supplier and not the one you're used to - so also practise singing along with the original artiste until you get fluent.