You can use Apple's PackageMaker, which is installed with the developer tools. I don't know of a good tutorial (sorry), but it is simple for simple installers.
However, consider if you even need an installer. When possible, you should make your app installable by letting the user drag-and-drop the app on to their local system. This is the preferred method of installation of apps on OS X.
A nice way to do it is to distribute your app as a disc image. Put your app bundle at the top level, along with a shortcut to /Applications. Typically, you'd create a background image for the folder that says something like, "To install, just drag your app to the Applications folder." (Along with some arrows, for the people that don't even want to read that much.)