Does Windows ask you for a password when your computer starts? It should. If a password isn't required to access your account, you're leaving completely open to anyone else at your home or workplace things like your email account, saved files, etc.
Assuming you haven't configured Windows to automatically login, chances are you simply don't have a password set for your Windows account. You need to correct this by creating a password right now.
The specific steps you need to follow to create a Windows logon password differ somewhat depending on which operating system you have so here are some how-to's specific to each version of Windows:
- How To Create a Windows 7 Password
- How To Create a Windows Vista Password
- How To Create a Windows XP Password
Note: It's always a good idea to create a password reset disk after creating a new password in Windows. See How To Create a Password Reset Disk for more information.
Tip: Trying to find a way to create a new password in Windows because you forgot it but can't get in to Windows (again, because you forgot your password)? You can keep trying to get in, using some of these guess your own password tips, or you can use a Windows password recovery program to crack or reset the password, after which you can then create a new password.