To lock and password in Window 7 follow below steps for that
1)To lock a folder, right-click on that folder and select Properties. Now navigate to Security tab, and click Edit
2) A new window will pop-up, now under “Group and User Names”, select the user from the list whom you want to deny access to a specific folder, now under “Permissions for Users” check the Deny checkbox next to Modify
3) Click OK and then click Yes when a Windows Security window will pops-up
4) Now click OK again and you are done. Now the specific user that you selected from the list will be denied access to this folder.
with this steps you can do it