C,C++,PYTHON

ı have mini 6410. which programming language is suitable for
beginners?

That depends on where you see yourself as a programmer in the future.

What kind of software do you want to develop?

C++, with all its features is probably the more difficult language but
becoming more "mainstream" in embedded development.

C is relatively straight-forward, but it steers you down an non-object
approach to coding.  That is not to say that you can't write good C code
using data abstraction, "setter" and "getter" functions, but the really
useful features of C++ are difficult, see ObjectiveC.
http://en.wikipedia.org/wiki/ObjectiveC

Python.  Had a play mainly using TkInter and I might look at WxPython for
some GUI stuff. I haven't found it that useful as most of my work deals
with hardware.  

Knowing C helps with the others, but if you are making a career out of this
I would suggest getting up to speed on C++.

http://en.wikipedia.org/wiki/Programming_language

My 2cents worth!

C would have to be your best option at least in terms of picking what is
rightful for someone who is just starting.  It was rather something that is
quite easy to understand at the beginning of it all as it was really
straight forward and would make for easier understanding always.  But in
any case that you see it fit, C++ is a viable option always.