What should i wear for my friends wedding?

Hi. please help me... What should i wear on my friends' wedding? they are getting married on 11/28 at 2:30 pm in a church then reception will begin at 6-11pm at a golf clubhouse. ive been asking them if it is formal party. but i haven't talked to them since. my husband is one of the grooms men and he's wearing a tuxedo. please help should i wear a casual dress? or an evening gown? or a gown? i have no idea. its the first time i'll be attending a wedding.