How can I find out if someone has a court appearance today? And if I can then what information do I need?

Check to see if that court publishes online a daily schedule. Some do, others don't. You can call the clerk of the court and ask them.

If the clerk will not give the info, if you are close enough to the court house, you can stop in and take a look at the docket for the day in question.

Our Court House posts this in the Small Claims/ Civil Court Clerks office and on the doors of the respective hearing rooms.

I'm not sure how many days in advance these are available though.