Although you have your own windows account in a computer, sometimes you have to protect some documents that are too secretive to be left un-protected. Word document has a password lock facility by which you can make that DOC file open only when you type in the saved password.
To assign a password to a doc file, open the required file and click on tools present the top menu and then click on options present at the bottom.
While I’m talking about a Microsoft word 2003 edition, you can easily find relevant commands in any version of MS word.
Go to Security tab after you clicked on the options in the last step. There you can type your password which will be required to open the document. You can also have a password required to modify the document. Save the changes.
If you need further protection, you can choose the advanced settings where you can encrypt the document properties.