Hallo Steve -
Don't be concerned about being 'dumb' - it can take a while to work your way around a messageboard. I've moved your post to a thread of its own, but for future reference, if you scroll down to the bottom of the pages listing threads for each part of the forum (in this case 'Passengers'), you'll see a link that says 'start new thread.' Click on it, and you'll find it does what it says on the tin.
I'm assuming you've already looked at the information for Tobin on the main site. Someone here may be able to assist you further, or you may want to contact the author of The Irish Aboard Titanic, Senan Molony.
Usually, if trying to trace a connection to an ancestor, it's better to start with what you know about your own immediate family and work backwards through family memories, birth, death and marriage certificates, obituaries and so on. This can be somewhat difficult in Ireland due to the destruction of certain records, particularly in the Irish War of Independance and the Irish Civil War.