Ok have my temp sensor working , how can I hook it to my 4 x 20 screen??

I have now got my 18B20 temperature sensor working with my arduino. The temp display at the moment is only on the computer at the moment via the serial monitor.

How can I now make this portable via using my 4 x 20 lcd display? it is a ic2 display. Are there any tutorials I can follow that will show me how to display the
temperature on the lcd screen?

it is a ic2 display

I don't know, you haven't supplied any information other than it's resolution.

How can I now make this portable via using my 4 x 20 lcd display?

Once you know what display you have and have a library for it then replace your serial.print calls with an LCD.print call, or what ever the library requires.

http://arduino.cc/en/Tutorial/LiquidCrystal

ahh that sounds like it would make sense.

http://arduino-direct.com/sunshop/index.php?l=product_detail&p=332

Full info on this here
http://arduino-info.wikispaces.com/LCD-Blue-I2C