How can I move all of my photos from Iphoto to Photos?

You can create new Photos Libraries from your iPhoto Libraries. If you open an iPhoto Library in Photos, the Photos.app will create a new Photos Library from it.

See: Updating from iPhoto to Photos for macOS – Apple Support

There are several way s to open an iPhoto Library in Photos:

• Quit Photos, if it is running, then drag an iPhoto Library onto the Photo icon in the Dock. Photos will open this library.
• Or hold down the options key ⌥ while launching Photos. When the library chooser dialog appears, release the options key and select an iPhoto Library to open.