Your MacBook laptop computer uses Mac OS X, which has a panel that displays your running applications. If your MacBook is running slowly or not working properly, you can open up this panel to force quit applications. When you force quit an application, the MacBook sends a command for the task to be shut down regardless of what it's doing. You can fix performance issues or troubleshoot problems using this panel.
Click "Finder" in the dock.
Click "Applications" and navigate to the "Utilities" folder.
Double-click "Activity Monitor." Activity Monitor displays all the Mac's running processes. If a process is taking up too much system memory, you can highlight this process and click the "Quit Process" button at the top of the window.