yep, theres no retarded question, only retarded ppl.
t-bars is one of the best back thickness exerise behind deads and bb rows. t-bar rows are just like very other exerise,if you dont know what u are doing or letting your ego get the best of you then your asking for an injury. so start slow.
the best way to do t-bar rows is the ronnie style with a v hand and a bar in the corner.