Ok I'm going to profess my life to Christ.?

Ok the other day I was at church and told my preacher that I wanted to be saved and he said ok we can do it Sunday. THAT IS TOMORROW! so I was getting ready on what to say and when I told him he asked: give a short testimony as to how you accepted Christ as your Savior. What exactly does that mean? I don't really know is that like why you want to be saved or what? So what does it mean to give a short testimony as to how you accepted Christ as your Savior.