lcd help

I bought a 16x2 display and it uses a HD44780 driver chip. and it has a 14 pin standard optrex compatible interface. the problem is I cant get it to work. all I get is black squares. I tried a lot of diferent programs. i'm trying to hook it up to the serial port. I used pin 3 to pin 14 of the lcd. and I hooked up the power to it. so now i'm really lost. this is my first time with lcds. so some help would be great. and I cant figure out what do do with pin 3 of the lcd it says something about it uses negative voltage

Go here , visit the forum, guides etc. You'll be able to find some tips and links to a lot of info.