Hello Ahmad,
You'll need to post your app online so that we have a URL to access
it. If it's a web-based app or an app based on a web service like
Facebook, then that would be your URL. If it is some other kind of
program, you need to post it somewhere it is publicly accessible on
the internet. Services like Dropbox work fine for this.
Then go to
http://worldbank.org/appsforclimate, make sure you login,
and you should see a big "Create Submission" button on the right
side. That's the submission form. One of the required fields is the
URL where we can access your app.
Tim