The hand tool (shortcut H) and zoom tool (shortcut Z) can be used as soon as you have loaded your image into Photoshop. Under the option bar shown above you will find several useful commands.
Actual pixels will increase your image to show the pixels 100% zoom ratio, this is the most accurate view as you can see your image as it really is. Double clicking on the zoom tool or pressing ctrl+alt+0 will also open your image up to fit on the screen
Fit on screen will size your image to fit on the screen. Double clicking on the hand tool or pressing ctrl+0 will also open your image up to fit on the screen.
Print size this command will display your image on screen at the size it will print.