Which program is best for a new user
I managed to find these four in about two minutes browsing through the programming forum. Hope something in here gets you started! 
http://www.idevgames.com/forum/showthread.php?t=9890
http://www.idevgames.com/forum/showthread.php?t=9607
http://www.idevgames.com/forum/showthread.php?t=9393
http://www.idevgames.com/forum/showthread.php?t=9178
Basically what you need to do is consider what program you want to make. Not all the specifics but a general idea. Is it a simple 2D puzzle game or a 3D first person shooter? Once you know that you can look into APIs and languages. As far as literal applications that you'll use, for coding you can do everything in Xcode (free from Apple) or a number of other programs. Technically you could just use TextEdit and the Terminal to do everything but that's a bit advanced if you don't know what you're doing.
As far as languages and APIs (All in my opinion of course. Other people may have differing views):
If you were making a 2D puzzle game, I would strongly suggest using something like the Cocoa API with the Objective-C programming language. For more advanced programs (such as the example of 3D first person shooter), you would consider your need for cross-platform ease (how easy it would be to take your game and put it on a computer not running Mac OS X). If that need is high, your best bet would be going with the SDL API along with the OpenGL API with the C/C++ programming language.
Each language and API is designed for different things. Cocoa allows easy integration with Interface Builder for quick creation of your window and the things you want in it. SDL makes cross-platform programming easier. OpenGL is a great API for graphics (especially 3D) that is also cross-platform. I believe OpenGL is also the only (and if not, it's definitely the most used) 3D graphics API for Mac OS X.
Everyone has their own advice and two-cents. Now you have mine along with some links that can get you started. Good luck!

http://www.idevgames.com/forum/showthread.php?t=9890
http://www.idevgames.com/forum/showthread.php?t=9607
http://www.idevgames.com/forum/showthread.php?t=9393
http://www.idevgames.com/forum/showthread.php?t=9178
Basically what you need to do is consider what program you want to make. Not all the specifics but a general idea. Is it a simple 2D puzzle game or a 3D first person shooter? Once you know that you can look into APIs and languages. As far as literal applications that you'll use, for coding you can do everything in Xcode (free from Apple) or a number of other programs. Technically you could just use TextEdit and the Terminal to do everything but that's a bit advanced if you don't know what you're doing.
As far as languages and APIs (All in my opinion of course. Other people may have differing views):
If you were making a 2D puzzle game, I would strongly suggest using something like the Cocoa API with the Objective-C programming language. For more advanced programs (such as the example of 3D first person shooter), you would consider your need for cross-platform ease (how easy it would be to take your game and put it on a computer not running Mac OS X). If that need is high, your best bet would be going with the SDL API along with the OpenGL API with the C/C++ programming language.
Each language and API is designed for different things. Cocoa allows easy integration with Interface Builder for quick creation of your window and the things you want in it. SDL makes cross-platform programming easier. OpenGL is a great API for graphics (especially 3D) that is also cross-platform. I believe OpenGL is also the only (and if not, it's definitely the most used) 3D graphics API for Mac OS X.
Everyone has their own advice and two-cents. Now you have mine along with some links that can get you started. Good luck!

