i can't get hello world to happen

Hello! I'd thought I'd jump into programming for the first time with a simple hello world but I seem to have run into a bit of a block. I can't really recognize the problem but if anyone would be willing to help out, many thanks. code provided below.

#include <LiquidCrystal.h>

char rowTop[] ="hello world ";
char rowBot[] =":^) ";

void setup(){
lcd.init();
//turns on backlight
lcd.backlight();
}

void loop(){
//start position for text
lcd.setCursor(16,0);

//top text scrolls left
for(int pos =0; pos < rowTop.length; pos++){
lcd.scrollDisplayLeft();
lcd.print(rowTop[pos]);
delay(150);

//wipes data from display at set location
lcd.clear();
lcd.setCursor(15,1);
}

//bottom text scrolls left
for(int pos =0; pos < rowBot.length; pos++){
lcd.scrollDisplayLeft();
lcd.print(rowBot[pos]);
delay(150);

//wipes data from display at set location
lcd.clear();
}

}
}

If you can't get text to appear on the LCD, why would you then add a bunch of code to make the non-appearing text scroll?

Get rid of all that crap.

void loop()
{
   lcd.print("Hello, Jupiter");
}

If that doesn't work, you are wasting your time trying to make text scroll.

Did you notice that the code doesn't compile?
And that you didn't post it in code tags (see How to post code properly )

Pete

There is no lcd object in your code.

LiquidCrystal lcd(12, 11, 5, 4, 3, 2);

The pin numbers depend on how it is connected.

See the "hello world" example in the IDE (file -> examples -> liquidcrystal -> helloworld). Get that working first. Next you can copy it to your sketch and use it as a starter for your own code.

PS
Next time please post error messages (if any). The below when I attempt to compile your code

C:\Users\sterretje\AppData\Local\Temp\arduino_7f65fe329e430c1eee4745ea793abe10\sketch_feb05a.ino: In function 'void setup()':

sketch_feb05a:8: error: 'lcd' was not declared in this scope

   lcd.init();

   ^

C:\Users\sterretje\AppData\Local\Temp\arduino_7f65fe329e430c1eee4745ea793abe10\sketch_feb05a.ino: In function 'void loop()':

sketch_feb05a:16: error: 'lcd' was not declared in this scope

   lcd.setCursor(16, 0);

   ^

sketch_feb05a:19: error: request for member 'length' in 'rowTop', which is of non-class type 'char [18]'

   for (int pos = 0; pos < rowTop.length; pos++)

                                  ^

sketch_feb05a:31: error: request for member 'length' in 'rowBot', which is of non-class type 'char [11]'

   for (int pos = 0; pos < rowBot.length; pos++)

                                  ^

C:\Users\sterretje\AppData\Local\Temp\arduino_7f65fe329e430c1eee4745ea793abe10\sketch_feb05a.ino: At global scope:

sketch_feb05a:42: error: expected declaration before '}' token

 }

 ^

Using library LiquidCrystal at version 1.0.4 in folder: C:\Program Files (x86)\Arduino\libraries\LiquidCrystal 
exit status 1
'lcd' was not declared in this scope
char rowTop[] ="hello world      ";
for(int pos =0; pos < rowTop.length; pos++){

Are you making up new C++ syntax as you go along ?

You have used the wrong syntax to find the length of a String (capital S) and applied it to a C style string (lowercase s)