We do not do your homework: it is set for a reason. It is there so that you think about what you have been told, and try to understand it. It is also there so that your tutor can identify areas where you are weak, and focus more attention on remedial action.
So start by looking at either a Regex (Search for "Regular Expressions c#") and get a copy of
Expresso[
^] - it's free, and it examines and generates Regular expressions, or look at the string handling functions: string.Split, string.IndexOf, and string.Substring methods.
Try it yourself, you may find it is not as difficult as you think!