I am a web programmer and I work mainly with ruby on rails and javascript jquery, and so on.
Now I would like to build a program for mac.
Which languages do I need? C++, Objective C?
For info and good beginner tutorials I would be very grateful.
You could use any language you like. My recommendation will be Java
since it can be learned very easily and OS X
comes with java pre-installed. However for Mountain Lion, you'll have to install java by yourself.
See
The best tutorials that I have seen on programming particular to the Mac OS X environment are:
http://en.wikibooks.org/wiki/Programming_Mac_OS_X_with_Cocoa_for_Beginners http://www.youtube.com/user/AppleProgramming
Also if you like to read books, the tutorial books from Big Nerd Ranch are quite good:
http://www.bignerdranch.com/books
Especially check out the "Cocoa Programming for Mac OS X (4th Edition)" book.