1. Before start using this tutorial, provide following command in Command Prompt:

bcdedit /set {bootmgr} testsigning on

It'll enable Test signing feature for boot screen and you'll not face any problem while using this tool.

2. Now download Windows 7 Boot Screen Editor and run the program's exe file.

3. If you want to change "Starting Windows" and "© Microsoft Corporation" text shown in boot screen, simply uncheck "Animation" check box and then customize the text given in "Text" section according to your requirement. At last click on "Go!" button. It'll take a few seconds and you can restart your system to take affect.

4. If you also want to change the Windows flag animation shown in boot screen, you'll need to create the animation. The animation can be a single 200x21000 px BMP file or you can create 105 BMPs, PNGs, GIFs, or TIFFs files and put them in a single folder. Make sure all the files must be the same format and will be played in alphabetical order at boot screen (so if you are numbering them, use three digits always, e.g. 000, 001, ..., 103, 104).

Click on "Select Animation" button in "Animation" section and select the folder containing your images and click on "Go!" button. It'll take a few seconds and you can restart your system to take affect.