Off the cuff, with so little information, I would bet that if you are using the two wire unit, then one wire goes to 5V the other to A1 through A5, analog input. The Arduino can read analog values between 0 and 1023, the voltage you register in the analog pin will convert to the bars of pressure in the provided chart from the pdf file you provided. If you are using a three wire system then one wire will be 5v, one will be ground, and the other signal, but you will likely have to take readings in pairs, from the chart it appears that at extremely low pressure you will actually be receiving a two number code to calculate the pressure. Simply use a Select Case routine to output the pressure based on the voltage returned from 5v to A1.