Here is how to log V4.5 in:
1) Go to Tamagotchi.com
2) Scroll down until you see a tab saying open.
3) Click on it and select V4.5
4) Go to the heart on the Tamagotchi.
5) Select PC.
6) Enter your username you put into the Tamagotchi. (It Tells you in the status menu too.)
7) Enter the login password on your Tamagotchi.
8) When you are done playing, click log out on the website.
9) On the Tama press the middle button.
10) Enter the log out password shown on the website. (scroll through the characters with the A button, press B to confirm.)
11) The website now displays passwords you may enter into your Tamagotchi.
And Thats it! Hope I helped.