Here after creating all the lines using the spline tool that can be found in "create > shapes > spline". I then clicked on one of the quads and then went on the modify panel then clicked on the right mouse key and scrolled down to "convert to > Editable poly" this then creates a surface of the line and it has now become a single polygon. I then attached all the lines together that can be found in edit geometry.

You can see in the image that a surface has been created and to see the splines that I have created by clicking on the viewport name an clicking on edged faces to show those splines that were created.