To add someone to a security group, so they can view a dashboard panel, you'll need to do the following (if you have the right permissions):
Click on the key next to the Security Console option, via the drop down menu in the top right hand side of Rapport (see screenshot below - if you can't view these, do let me know and I can send these as attachments)
Once Rapport has refreshed, click on the panels icon just above the very top panels on the right hand side (this will open a pop-up).
Select a panel on the right hand side by clicking on it, and then select the key circled to load the security console for that specific panel (this will load a second pop-up screen).
Select the security group you want to add the person into and then select the option EDIT GROUP MEMBERSHIP (this will open up a third pop-up).
Click on the name of the person you want to add on the left, click on the arrow pointing to the right which will move them over to the right hand side, and then click on the save icon (the blue floppy disk) on all three pop up screens to provide them access to the panels. Make sure that the group you add the person to has access to the panel via the second pop-up screen.