You can select the fields that you are searching for candidates in, the programming language of the potential repositories and the popularity measure (how many "stars" and "forks") of potential repositories.
You can also click "more" to narrow down the potential repositories by adding time restriction.
After you click "Search Talent Now", it will generate a list of repositories that you might be interested in. Choose one and click.
You might see the profile of this repository and the contributors, which are potential candidates you want to find. In this example, there are 77 contributors of this repository.
Choose one contributor and click on his profile page.
Remember to check Hiretual's Extension in Chrome!