I have to learn to give a internet browser right into a cacao application. (Mac)

Try WebKit. Particularly, you will probably find the MiniBrowser example that accompany the developer tools interesting. It ought to be at /Developer/Good examples/WebKit/MiniBrowser.

It's not so difficult:
1) give a WebView resist your interface builder project.

2) (this is actually the important part) make sure to implement the needed delegate techniques and hang your applying class because the WebView delegate (in IB). I do not recall exactly, however i think you will find like 6 techniques you have to implement inside your delegate... it will just work. (obviously, look into the example code...)