There are a few ways to add shape to Illustrator files. One way is to use the Polygonal tool. The Polygonal tool can be used to create polygons, which are shapes that have a specific shape and size. You can also use the Rectangle tool to create rectangles, and the Circle tool to create circles. Another way to add shape is by using the Stroke tool. The Stroke tool can be used to draw lines, arcs, and other shapes. You can also use the Brush tool to paint over areas of your file with different colors or textures.
