Hi agnes
I'm confused it sounds as though the injection they are talking about is either Byetta or Victoza which is for T2's as it relies on having the ability to produce insulin so can't see how it would work for a T1!
Carbs wise, you need to learn the carb counting so that you can adjust your insulin need appropiately to the carbs you eat, also you need to consider other factors, such as exercise so that you can adjust your dose of insulin to compensate for how this effects your blood glucose levels, so that you don't end up with an hypo or an high bg..