I think everybody know how to rename a file in Windows 7, just right click on the file and click rename and next type what name you want to or left click on file and then press F2 from keyboard and finalize it with press ENTER from keyboard. How if you have many files that all of them have identically same and for any reason you want to mass rename them? Actually Windows 7 has ability to do it.
Almost same way to rename a file but it just need to select all file you want to rename and then do as rename single file. For complete tutorial, here is step by step how to rename multiple files in Windows 7
1. Select all files that you want to rename, press CTRL from keyboard and click what files you want to rename with left click from your mouse
2. Press F2 from keyboard, another option you can right click mouse and click rename
3. Type what name you want for first file and press ENTER
4. Automatically will change all selected file to new name with extra number
I usually use this way for rename all serial movies in my computer which I have one file for one episode so I just naming it with movie title with extra number (automatic) base on episode. Enjoy it!