How do I add an icon to the right-click menu?

Question

As you probably know, you can right click files and it will show you options, such as run as administrator. I added "Run Sandboxed" to it by making the key Computer\HKEY_CLASSES_ROOT\exefile\shell\Run Sandboxed\command an adding the value C:\Program Files\Sandboxie\Start.exe %1 to (Default). If I right-click an exe file, there is something that says "Run Sandboxed", which runs the file sandboxed. It doesn't have the Sandboxie icon next to it. How do I add the icon?