Once you've downloaded Localize Internet App, you'll see "My Apps" under the App Center in the left column of your Weebly editor (where the elements are). Click that or alternatively go to Settings -> My Apps. Click "MANAGE" tab on the right. Click that and you'll came to sign up page where you can start your FREE TRIAL by adding asked information. You have one week free trial to test and fall in love in Localize Internet and you may cancel anytime without any charge.
NOTE: Make sure your Weebly site is published when you start using Localize Internet. Later you can unpublish your site if you wish.