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