Listening to 'Open Your Heart'...
There's something very strange going on. I'm hearing the vocal wandering around the stereo stage, almost as if you have an auto-panner on it. This needs fixing.
I suspect that this could be about your recording the vocal as a stereo track and then falling into some sort of mono/stereo trap - maybe adding a mono insert processor to a stereo track? You could convert the stereo vocal track to a mono one, but a quick fix would be to route the stereo track to a mono Group track, pan the stereo track hard to one side, and then do all your processing in the mono Group. Make sure that you remove all processing from the stereo track.
As to the vocal... It is performed reasonably well, but it does need some tuning work. To do it properly you will likely need Cubase's VariAudio to help you out. It's a bit advanced, maybe, based on where you are right now, but maybe it would be worth digging into it as a learning exercise. Failing that you could try Cubase's Pitch Correct as a quick fix and see how that sounds.
To the mix... The vocal is much too loud in relation to the backing and need some dynamic control to sit it back into the mix. Tonally it's not bad, but there's a fair bit of mid resonance that would be worth taming to remove the sense of congestion. The reverb sounds a bit too heavy to me, but with the vocal sitting back in the mix it might work.
The intro piano is very loud, then the backing drops down in volume, which sounds strange. Both the intro and ending are not at all helpful and they sound glued on. The sounds in the intro and ending are also not at all good. I'd lose both of them.
Keep at it - you are at the start of a wonderful journey!
