The 4-bit library is in the playground - I used the one from neilzero. There are two data sheets available from Spark Fun, the short one has backlight wrong, the longer one has it right. Don't worry, if you hooked it backwards you didn't fry your LCD - I did it!
One thing I remember is the RST line must be connected to ground.
Also, the library functions expect NUL-terminated strings. If you don't add a NUL, it will display lots of garbage.
Good luck!