How to put a pass word on my Lenovo lap top so that no one else can use it?

It depends what operating system you are using - windows 7? Windows 8? Windows 10?

In general
Open User Accounts by clicking the Start button, clicking Control Panel, clicking User Accounts and Family Safety, and then clicking User Accounts.

Click Create a password.

If there's already a password for this user account, you can change it by clicking Change your password.

Type the password in the New password box, and then type the password again in the Confirm new password box.

If you would like to use a password hint, type the hint in the Password hint box.

Click Create password.

Are you running a Windows operating system? If so, the help button for any version of Windows you have will tell you how to create user accounts and how to set them with a password.

The basics will go something like this:
Open User Accounts by clicking the Start button, clicking Control Panel, clicking User Accounts and Family Safety, and then clicking User Accounts.

Click Create a password. Type the password in the New password box, and then type the password again in the Confirm new password box.

If using Windows, hit control-alt-and the delete keys at the same time. And there she be (since the 1990's).