doubt about sensor

Hi to all! i’m new in Arduino’s world. I have a problem. I have a sensor and the output is serial in format XYYYYY XYYYYY XYYYYY XYYYYY, where X is a letter and Y are numbers, and the data is transmitted continuosly. The problem is i want to capture only a field and store it in a memory. It should be a good idea use pin o and pin 1? This project must be stand alone without any link with pc. Any suggestions about code? thanks in advance.

How about some clues as to what exactly it is you are connecting it to and what it is you want it to do?