When you open the Mac application, you will see a small Jargonnay icon on the toolbar of your Mac. You can Sign In by clicking on the "Sign In" option on the toolbar.
If you open the Jargonnay app and you are also signed in, you wil see the toolbar similar to the image on the right hand side. This means that the Jargonnay app is running and you are signed in. You will also see an option to "Go To Dashboard" which will open the web dashboard.