So here is a really simple example that will get you started. To try this create a new default Alloy app and then use the bold filenames to create a new file and then copy the code in, add new files as required. Important; removed the contents of the index.tss but leave the file - just in case anything conflicts, will not kill anything, just may…

app.tss

"Window": {
    backgroundColor: '#fff'
},
"Label": {
    color: '#000',
    font: {
        fontWeight: 'bold'
    }
}

index.js

if (OS_IOS || OS_MOBILEWEB) {
    // attach the navgroup to Alloy.CFG so it can be accessed globally
    Alloy.CFG.navgroup = $.navgroup;
 
    // We can do most of this in markup once we resolve:
    // https://jira.appcelerator.org/browse/ALOY-202
    //
    // TODO: find out why nav buttons and titles don't work for mobileweb
    var button = Ti.UI.createButton({ title: 'next' });
    button.addEventListener('click', function(e) {
        $.navgroup.open(Alloy.createController('win2').getView());
    });
    $.win1.rightNavButton = button;
}
$.index.open();

index.xml

<Alloy>
    <Window id="index">
        <NavigationGroup id="navgroup" platform="ios,mobileweb">
            <Window title="Window 1" id="win1">
                <Label>This is the first window</Label>
            </Window>
        </NavigationGroup>
        <Label platform="android">NavigationGroup not available on Android</Label>
    </Window>
</Alloy>

win2.js

// We can do most of this in markup once we resolve:
// https://jira.appcelerator.org/browse/ALOY-202
var button = Ti.UI.createButton({ title: 'next' });
button.addEventListener('click', function(e) {
    // Access navgroup from Alloy.CFG, set in index.js
    Alloy.CFG.navgroup.open(Alloy.createController('win3').getView());
});
$.win2.rightNavButton = button;

win2.xml

<Alloy>
    <Window title="Window 2">
        <Label>This is window 2</Label>
    </Window>
</Alloy>

app/views/win3.xml

<Alloy>
    <Window title="Window 3">
        <Label>This is window 3</Label>
    </Window>
</Alloy>