How did you design the power amplifier if you didn't simulate it already to see the PAE,Pout etc? May be you did it using ideal closed-from equations. But anyways, this is how I do find these parameters:
Since, measuring these many parameters means writing loads of equations, I use design guide available in ADS to get these parameters. For example, open
Design Guide>Amplifier>Power Amplifier Examples- By class of operation> Class AB>Spectrum, Gain, TOI, and 5th OI points and PAE vs Power
And replace the example class AB with your designed PA , do couple of changes in the schemeatic as per your specs, (also you need to modify the load/source settings in schemtic as you have already design the complete PA), and then hit F7 and you have it !
If this design guide seems complicate, begin with a more simpler design guide that just measures PAE and Pout. Play around with various design guides until you're comfortable with them and you will quickly learn great many stuff.
And some people also use template from dds (plot) window: Insert> Template
etc.