Help with unity files

hi,i am working on a project in unity 4 and i need to save it as a "unity3D"file. How do i do it, because whenever i try save it, it saves as a “unity” or a “exe” file.

unity3d are files generated for browser. You have to change your platform settings to Web Player (File->Build settings… then select Web Player, click Switch Platform), and then build your project.