With reference from @HSNR,
I use the latest OpenEmr Version
I tried to change the Login-Logo :
In this version you can find it on
The name of the Login-Logo is login-logo.png
I delte it and copy my own login-logo in this folder.
I named it also login-logo and it`s a png.
Also it has the same size as the old one.
But still when i went to my login-page its the old one.
I don`t know were my failure is.
I am pleased about answers.