how to transfer pictures from iphoto to photos on imac

Open your iPhoto Library in the Photos.app. There are several ways to do it:

• When you first launch Photos it will open the last used Photos Library. Just double click the Photos icon in the Dock.
• Or drag the iPhoto.app from the Applications folder onto the Photos icon in the Dock.
• Or hold down the options key ⌥ when launching Photos to bring up the library chooser dialog. Then pick the Photos Library you want to open in Photos.