1993 Chevy Beretta Replacing the front brakes

Brakes problem
1993 Chevy Beretta Front Wheel Drive

Me and my aunt recently tried to change the front brakes on her car and we got the old brakes off and had problems getting the caliper onto the roter. After we got it on, the caliper bolt holes didn't line up, so we got them lined up after 3 hours and out it all back together, and she took it for a test drive and it screeches when you hit the brakes. We made it worse than it was! Do you have any suggestions on this problem? We are new at this and neither of us have had any experience changing brakes, only watched them get done before.