To add icons to the dashboard you will need to build your own custom dashboard by creating a new dashboard project (this can be done from the Getting Started Windows in LabVIEW). You can then copy and paste images to the front panel of the VI.
For your dashboard to show up as the default one launched by the driver station you will need to built your dashboard into an .exe (this can be done under Build Specifications in the project) and place it in the default directory for the dashboard.
More general information on the dashboard and its use can be found here:
https://decibel.ni.com/content/docs/DOC-26296