Question: pcsx2 how to run iso?
Answer: Go to CDVD > ISO Selector > Browse, as shown below:
Navigate your computer for your PlayStation 2 ISO. Click on it, then click Open. *Note: PCSX2 only supports ISO, BIN, IMG, MDF, NRG. ... 
Go to System > Boot CDVD (full). Wait a few moments and your game will load. Enjoy!