getting better at Debugging and finding out WHY?

hi.. i'm new to titanium appcelerator..and well.. programming.. mainly app programming

i'm having trouble finding out why my code dosen't work.. how i can fix it...

so my question is..

does anyone have a good link or tutorial on how to get better at spotting my errors.. even just a starting point would be nice.. because i have no clue on how...!!

some guidance please..

please help a lost soul..

for example:

function createTab3(){
    //
    // create base UI tab and root window
    //
    var win3 = Titanium.UI.createWindow({  
        title:'ding dong',
        backgroundColor:'#fff'
    });
 
    var tab3 = Titanium.UI.createTab({  
        icon:'KS_nav_views.png',
        title:'ding dong',
        window:win3
    });
    Ti.API.info(mapview);
    /*var region = {
        longitude:      
    };*/
 
    var mapview = Ti.Map.createView({
        maptype: Ti.Map.STANDARD_TYPE,
        region: getLocation(),
        animate: true,
        regionFit: true
    });
    function getLocation(){
        Ti.Geolocation.getCurrentPosition(function(e){
            var region = {
                latitude: e.coords.latitude,
                longitude: e.coords.longitude,
                animate: true,
                latitudeDelta: 0.005,
                longitudeDelta: 0.005
            };
            Ti.API.info(region);
            return region;
        });
    };
    win3.add(mapview);
    return tab3;
}
module.exports = createTab3;