You should then see a settings screen for your app which looks a little bit like this:
Make sure the contact email field is correct. Under App Domains, enter your host's main domain name. For example, a game hosted at http://www.scirra.com/games/mysupergame would enter scirra.com as an app domain.
The checkboxes along the bottom determine what type of app you're publishing. Since your game is hosted on a server as a web app, there are three options you can check: Website with Facebook login, App on Facebook and Mobile Web. It is recommended to check all three, but you can check fewer if you want (e.g. if you don't support mobile).
For Website with Facebook login, enter your web app's URL. For App on Facebook, enter the URL to the game again, which Facebook will display in an iframe. Your game should be set to use a fullscreen in browser setting (e.g. letterbox fullscreen). Then you can set both Canvas Width and Canvas Height to fluid, so the game will use all available space. For Mobile Web enter the URL again, and leave payments disabled (Construct 2 does not currently support this).
Note that Facebook apps require a secure host (a URL beginning with https://) for security reasons. Contact your host for help getting this set up.
If any of your URLs are rejected as invalid, try making sure they end in a slash or query string. For example, if https://example.com/index.html is rejected, try entering https://example.com/ or https://example.com/index.html?s=1 instead.
Some servers will return a Error 405 - HTTP verb not allowed error when previewing from within Facebook. This happens on PHP or ASP.NET servers where it is not expecting Facebook to POST to a static HTML page. To work around this, copy and paste the index.html file on your server, and rename it to a dynamic page (e.g. index.aspx or index.php). Then change your app URLs to point to the dynamic page.
Click Save changes. Next we'll set up the app's basic info.