audio file editing in c#

Question

Dear sir/madam

              Hai, this is koteswari, iam trying to develop an academic project on audio editing in c#.net, i developed upto loading, playing and drawing wave form on picture box, Know i want to develop cutting of these files, Please help me in below topics
          1. how to select cutted part using mouse click on wave form which is drawn on a picture box using bitmap.
          2. how to cut audio files using c#.net, and save them seperately.

Thanks & Regards
Koteswari