Two great books I would recommend:
CLR via C # Jeffrey Richter
and
Clear code from Uncle Bob Martin
Richter’s book will give you all the details about the aspects (programming and OOP features) of C #, and Martin’s book will give you recommendations on writing proper code in an OO environment. Martin's book is Java oriented, but the concepts apply equally to C # (IMHO).
Head First OOA & D, , . , .:)
, !