Ok, I have been wrecking my brain trying to learn the basics. Every example I do I get a blank page. I'm using a mac and safari to view also my iPad. I can see the title in the webpage but comes up blank.
Without more information it's hard to know exactly what the problem is.
Personally I found that the "Getting Started…" tutorial was a good one to begin with, even if it doesn't answer every question we might have about working with Ext.js:
If nothing else, that tutorial set me up with a proper workspace and a working application which I've been tweaking and modifying. I hope this helps.
I myself am using Chrome on a Macintosh, so I am not as familiar with working with Safari. One great thing about Chrome is the developer tools that come bundled with it. Being able to bring up a JavaScript Console so I can see where errors are being thrown is crucial. I strongly recommend that you preview your work in Chrome and when you come across a problem like the one you're describing, hit option-command-J and see if any errors have registered in your console. Often they'll even point to a specific document and line of code.