Can't design layout properly

Hello everyone,

I design page with VerticalLayout, which has  two objects  - label and a component (panel)
This is how i expect to make it look like (see final_bmp.png) attachment
And this is how it looks like (see looks_like.png) attachment

The code, how i archieved this (please note that singleton named 'componentHelper' only used to make certain components and nothing else):

@UIScope
@SpringView(name=ViewTokens.HOME)
public class SplashScreen extends VerticalLayout implements View {

    private static final float PANEL_WIDTH = 320;
    private static final float PANEL_HEIGHT = 140;
    private static final float BUTTON_WIDTH = 270;
    private static final float BUTTON_HEIGHT = 70;

    private ComponentHelper componentHelper;
    private Panel panel;
    private VerticalLayout formLayout;
    private Label welcome;
    private Button toLoginPage;

    public SplashScreen() {
        initComponents();
        buildSplashView();
    }

    protected void initComponents() {
        componentHelper = ComponentHelper.getInstance();
        panel = componentHelper.createPanel("", PANEL_WIDTH, PANEL_HEIGHT);
        welcome = componentHelper.createLabel("Welcome");
        formLayout = componentHelper.createVerticalLayout();
        toLoginPage = componentHelper.createFriendlyButton("To Login Page", BUTTON_WIDTH, BUTTON_HEIGHT);
        toLoginPage.addClickListener(this::redirect);
        }

    private void buildSplashView() {

        setMargin(new MarginInfo(true ,true ,true ,true));
        setSpacing(true);
        setHeight(100, Unit.PERCENTAGE);
        setWidth(100, Unit.PERCENTAGE);

        addComponent(welcome);
        setComponentAlignment(welcome, Alignment.MIDDLE_CENTER);
        addComponent(panel);
        formLayout.addComponent(toLoginPage);
        formLayout.setComponentAlignment(toLoginPage, Alignment.MIDDLE_CENTER);
        panel.setContent(formLayout);
        panel.setStyleName(ValoTheme.PANEL_BORDERLESS);
        setComponentAlignment(panel, Alignment.MIDDLE_CENTER);
        setHeight(100, Unit.PERCENTAGE);
    }

Please help me.
Would be great, if someone also explained the logic of layouting ( i read Vaadin Book before asking this)