Thank you everyone and for suggesting how I align the bike. Here is the photo of the screw I mentioned earlier; I have removed it and now use the nut to tighten the wheel.


I guess I didn't put the tube in correctly - here is the video of what I mean when I said it was wobbling https://photos.app.goo.gl/JyRsSH2dP7VAuDdr5



Hope I can ask a couple of more things:

* I am trying to find a single speed chain to replace the one I have. I am only finding 3+ speed chains and I was wondering I can get any chain and size it?