As I mentioned in my answer to your other question, you cannot use message boxes or console.writes to see information from an event system in SDL Tridion. You will have to revert to logging to the Tridion Event Log or debug your event system.
Remote debugging is possible as described in this msdn article, but I usually find it a nuisance to setup (provided you are not being blocked by firewalls between your dev machine and the CMS). So normally I simply revert to just instaling Visual Studio on the dev CMS server and debug the event system DLL directly from there, by attaching to the dllhost.exe process (see more details in this blog post).
And like I also mentioned in my answer to your other question, I'm still not convinced you can achieve your requirements in an event system. You might need to look at a UI extension or something completely different for logging active logins of a user. Technically, you are never logging into the SDL Tridion UI, since your password is validated by IIS, and not by the SDL Tridion web application.
ps. its better to edit your question if you want to give more info, its never a good idea to open up a duplicate question.