[Satcomer]

Well follow these steps (since you have a Tiger (10.4.11) these are the steps). I will try to be right to the point.

1. Ask the person who sold you the Mac what Username did he give the Mac when he formatted it before he sold it. This is VERY import!

2. Find the Power button.. With the other hand hold the two buttons Command (apple key) button + the letter S (at the same time) while booting up the Mac.

3. Hold down the command + s until you see a black screen with white scrolling letters. Let go of the buttons at this point.

4. At the prompt sign (where you can type) type:
fsck -y

Let that run (it will run for about 5 to 10 minutes) until it reports all is well with the disk. At the point of this it will give you another typing prompt.

4. Type: mount -uw /

Then hit the 'return' button.

5. At the next prompt type: sh /etc/rc

Then hit the 'return' button.

6. At the net prompt type: ls /users

Then hit the 'return' button.

7. At the next prompt (at this point you NEED to have the Username the person made on that Mac) type: passwd (your Username without the quotes )

At this point it should ask you to type the new password for the Username you used. It will ask to type the new password one more time to make sure it is good before it changes the password. If all goes well and the change is successful you can type: reboot at any prompt to exit single-user mode and reboot the Mac into normal mode.

Lastly at the login page you will be able to use you new password to login. If you can login go you system Preferences (in the Dock) and launch it. Choose the "Accounts" pane to change the user preferences about logging in. What ever you DON'T change the current logged in User name at any time. Just make a new Administrator account and then login to that new Account and then you can go to the same place and then delete the Username that is not yours.

I hope this helps because it the best I come up with at this time of night before bed. Good Luck.