You can shade the surfaces to get a clearer idea of what the finished surfaces will look like.
on the View toolbar.
on the Draw toolbar.
on the Draw toolbar to hide the surface boundaries and internals. The model will look like this:

As you can see the last surface you created is wrongly orientated. The surface is displayed in red, which means you are looking at the inside of the surface rather than the blue of the outside. In the next section we will reverse the surface so that they are both orientated the same.