C# is indeed a part of MS .Net programming languages family and is derived from C++ and Java. It's specifically designed for use under the Windows platform but there is a project named "Mono" which allows you to write C# code under Linux.
On the other hand, C++ is the language Linux relies on and most (if not all) Linux distros come with a C++ compiler. You have several choices for C++ IDEs under Linux such as anjuta or KDevelop (the most popular).
There are many sites that can get you started with C++ (doesn't have to be tutorials specifically written for Linux, C++ is the basically the same under both Linux and Window$). Just google for 'C++ tutorials'.
For the beginning you can take a look at one of this sites: 1
and some reference for C/C++ here
Looks like _J got ahead of me.