First, open the CDA software. If you want to modify the original drawing, select Open. If you want to draw a new drawing, select New. In the extension tool in edit mode, according to the actual requirements of CAD drawing, you can click and select the lines to be edited. The menu bar above the software provides various drawing tools. If you need to create multiple different layers, set different line styles and adopt different line colors, you can choose "Layer Manager" in common functions to set them in edit mode. If you need to modify the content of CDA diagram, there are corresponding modification commands to choose from in the extension tool of editing mode. After drawing, click the icon in the upper left corner of the software interface, and select "Save" or "Save As" from the drop-down menu to save the edited drawing.