Write XML and java files for an Android project that displays a registration form similar to the provided screenshots. The form should include the following:

$1.$ Displays logo at the top of the form. The logo must be fixed while scrolling.

$2.$ Include a ScrollView, several TextViews, EditTexts and a Button. When the user clicks on the button, a message should confirm the registration process using the entered username.

$3.$ Use appropriate layouts to arrange the elements.