Dear ameer,
Just click Material Stream then input your Feed Composition, Pressure,Temperature or Vap.Fraction, then click "Attchment" --> "Analysis" --> "Create" and choose "Envelope", finally click "Add" to add phase diagram (envelope) of your stream.
To see of your Phase diagram just click "performance", then u can choose systems diagram plot such as P-V,P-T,P-H etc.