Start off with a high level language such as python for example to master the basics of programming. Later, you can move on to C/C++ if you think you are ready. The C syntax is used in many other languages such as Objective-C, Java, C#.

Interpreters, compilers, runtime environments etc. are mostly written in C/C++. So you are good with C for reverse engineering operating systems.
Bear in mind however reverse engineering involves assembly programming which may be a bit difficult for beginners.

You better find a good book about programming and reverse engineering.
Make sure you practice a lot. Just reading the book won't help