I need desperate help on games for DC

I recentely aqquired some burned games and I think they were done on GDs but I am not sure. Is that even possible? Is it even possible that they were done on cds? If they were done on cds what would happen when I play them and will there be any weirdness? The games are Crazy Taxi one and Soul Calibur. I bought my dremcast in the month of june so how will I be able to play burned games? Will it screw up my system? Thanks for help.