Please open the profitui.jnlp file with Java WebStart. Usually it will launch automatically.
After launching a security message will pop up. The updater is not allowed to write to your hard disk without your permission.
If you leave the box checked, it will only ask you once til the certificate expires. If you want to check the signature for security reasons, its SHA1 fingerprint is 29:16:C0:81:95:D1:A6:2E:9A:95:09:87:1F:97:FA:F4:61:E5:DD:28. You can also crosscheck the fingerprint here.
This need to sign the files will also prevent the injection of malicious code even if the server gets hacked.
Java now starts downloading and starting the application. It will create a shortcut in your startmenu and on your desktop automatically. You do _not_ need to visit the website every time you want to launch it, just use the shortcuts. Further updates to the updater are fully transparent, since it automatically checks itself every time it is launched.
To uninstall, just go to Windows' system control and uninstall it like any other application.