subpoena question

Hi,

some guy just delivered a subpoena form to me, and it is related to something happened about 2-3 years ago. basically i was in that restaurant that night, and the parking attendant there was accused something illegal later (i don't know anything), and his lawyer called me about 1-2 years ago about the time period i was there, and now they gave a subpoena to "command" me to appear in the court next month, "disobedience of this subpoena may be punished as CONTEMPT by the court".

so i guess now i have to appear in the court that day? anything i should or should not say in the court? they asked me to call the lawyer's office tomorrow.

thanks

legallynewbie