The default OS X login for multiple users is the GUI (graphical user interface) login. You see a picture and click on it, and if necessary, you are prompted for a password. If you want to temporarily change from the GUI to the text based login screen, you can do it with a simple keystroke. Here is how to do it: From the GUI login screen, hold down OPTION + SHIFT + DOWN ARROW and then press RETURN. This will change the GUI to the text based login. Once you are at this screen, you need to type in your username & password (both case sensitive). Be sure you know your your username and password, since you have to type them in. Depending on how you have your mac setup, you may be able to hit the 'back' icon and go back to the GUI version. If not.. well, you may need to restart the mac. I couldn't do a screenshot of this, since I was not logged in -- sorry.