passing parameters to user control

i would like to pass a parameter to a user control, in order to create a button with a image.

the xaml code should look like this:
ImageName="test.png" />

and the object looks something like this:

public string ImageName { get; set; }

public ImageButton() {
            InitializeComponent();
            this.ImageName = ImageName;
            this.DataContext = this;
}

that has a xaml code like this:

and now i want to pass the test.png all the way down, so a can create buttons with different images.

i searched for some time, but i could not find something that i could understand. so i holp someone can help me :)