Your visual employs Automatic Shape Connectors, which draw lines for you. However, you may need to draw additional lines to connect some shapes. For example, there may be a backloop in the process.

Begin by clicking Draw Lines in SmartPanel. This transforms your cursor into a line-drawing tool, with the "Shape Connector" line shape selected.

Next, click on the edge of the shape from which the line will originate.

Click on the symbol you wish to connect to. As you approach the symbol, Connection Points appear along its border, indicating points where you can attach the line. Your cursor becomes an anchor icon, indicating that the line will stay attached to the symbol even if you move the symbol.

To add text to the line you've just added, begin typing while it's still selected.
