I want to find some newly-created Github projects which will be easy to understand and contribute to. But in GitHub there's only a "explore" function that lists the most popular projects. How do I find the projects that are not so popular or mature? Do I need to write a program to query their developer API for this information, or is there an easier way to find newly-created projects on Github? Thanks.
On their search details page github lists some ways to find this information:
https://help.github.com/articles/searching-repositories
You can filter repositories based on times of creation, or when they were last updated. For repository creation, you can use the created qualifier;
Example:
ruby created:>2014-01-01
Matches repositories with the word "ruby" that were created after Jan 1, 2014
Good luck, and I'm glad you are wanting to contribute to an open source project!