just install it, you don't need any instruction to apply this boot screen. Just install it like you installing a theme, after it turn off your phone, and turn on it again. You will see win7 boot screen also hear win7 startup tone.
Edit: you can change startup animation and startup tone. Use X-plore and look this folder.
1.Download 200159c0.zip 2.Gp To Mass Memory: \ Private \ 3.Delete 200159c0 From There. 4.Download Mine 200159c0 Zip File
5.Copy 2 Folders From 200159c0.zip And Paste Them To Mass Memory/Private/200159c0 6.On the Nokia N8, go to Menu> Settings> Phone> Phone mgmt. > Factory Settings> Restore