Why does my image have black lines? This is created using pen tool and I'm using Illustrator.
It sounds like you enabled outline mode. This is a mode that will break your image/design down to simple black lines, where you can see everything (even if it's behind an object). Commonly referred to as "outline or wireframe". You can toggle this view by pressing
CMD + Y(Mac) or
CTRL + Y(Windows) or
View > Outline in the top application toolbar.