sainsmart 3.2" +touchscreen

Hey people. I am absolutely new to this but I understand the basics (and only the basics).
anyway I got my hands on a couple of Sainsmart 3.2 inch touchscreens. I am currently waiting for a shield for them. the issue I have is I want it to recieve information through an rca jack, go through the arduino and be displayed on the screen. then to make it more fun I want the touchscreen part to send signals back (most likely through the usb connector). its a project I have for a raspberry pi. I can wire it all up but the programming side is getting to me. so please help with as much detail as you possibly can please

I want it to recieve information through an rca jack

What sort of information?
If it is a video signal then forget it, there is not enough memory or speed to do anything useful with it.

I am trying to get a sain smart screen as an add-on to an arduino board. the idea is raspberry pi ->arduino-> touchscreen-> arduino _> raspberry pi

I think a good starting point is to get the UTFT library and get the screen working.

http://henningkarlsen.com/electronics/library.php?id=52

UTFT is a really nice fast writing library with some really complete documentation and the sketches are good documentation too. There are a half extra fonts sets as well as several different sized Icon sets.

Bob

Ok maybe I forgot to put this in but my programming skills is as good as steven hawkings ability to run. We both understand the concepts but putting it into practise is proving difficult.
all I am after is a way to have the screen show what the PI is showing.I am assuming at some point I will need to put an rca plug on it or have someone design a driver for it to be run on usb but at this point I would like it to work on my pc at least

all I am after is a way to have the screen show what the PI is showing.

You should have said in the first place.
Forget it the arduino has no part in such a project. It is not fast enough and has not got enough memory.