You need to change the ownership and permissions to dull control in the file properties.

NT file system (NTFS)

Create a file and set it's permissions to 222

In short: a very good understanding of file and folder permissions. There is no clear answer to this question. Folder and file permissions are very complicated. You can individually control folder and file permissions by right clicking on the folder/file, select properties, click on security and click on 'Edit...'.

Be aware that this can have far reaching consequences. I suggest you go to http://technet.microsoft.com/en-us/ and learn about file and folder permissions. It is not easy and very tricky.

Select the file you want to change permissions for in the directory listing. Click on the Info icon in the toolbar, or select Get Info from the File menu. Change the permissions in the Info window. You can automatically set permissions when you upload a file. In the Preferences window select Server Options and tick the Set permissions of uploaded files box.