Upload your files through the Phone Gap build website, link your Phone Gap build account to your Github account, link the Phone Gap line command tool to your Phone Gap build account or use Dreamweaver to get started.
After you have uploaded your app you can download your app from the Phone Gap build site, share your link for others to download it or submit it to the app store.
Debugging a Phone Gap app is the same as debugging a website. You can use Chrome and their developer tools to debug or Safari as well. Safari, for iPhone, allows you to use an iPhone simulator so you can get the real feel of your app.