If you haven't already done so I suggest that you right click on the taskbar, and go to taskbar settings. Under "Notification area" you can "Select which icons appear on the taskbar". I suggest you disable those you don't use, and enable wamp, it should start with aetray or something similar.

It is also worth noting that different menus appear for WAMP depending on if you right or left click on the system tray icon. Please explore all of these options thoroughly! I suggest that you select "Display WWW menu" as this will give easy access to the folder in which you will install JOOMLA