We can know the GUID of an application by the following ways:
1. Find the GUID going to the register. The path where to find is: HKEY_LOCAL_MACHINE\ SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall\…
Here, if you click on F3 you can search the name of the application and you will see the GUID.
2. In SCCM 2012, In the Deployment Type of an Application. Go to the properties and in the Programs tab, click on the Browse button for Product Code and select the MSI file. Will appear automatically the GUID.