There are a few possible reasons for this:
You have only picked keywords where your website doesn't actually rank within the top 100 results. In this case perhaps try to change your keywords and/or improve the SEO of your site to rank higher.
You have entered the website's domain name incorrectly. The domain name needs to be the one that is indexed by Google. You can check this by doing a Google search for your website and looking at which domain Google shows. For example if your website is listed as example.com in the Google result and you have entered it as www.example.com, you won’t get any results.
You have selected the wrong search engine. For instance, if you have a Swedish website but you selected Google.es instead of Google.se, chances are you will not see any ranking.