Before themes are added to the WordPress Theme Directory, they are closely reviewed by the Themes team to make sure they adhere to basic guidelines. This review ensures that WordPress users across the globe can download themes that are high quality and secure.
If you have theme development questions, please post them in the Developing with WordPress forum. Volunteers from around the world are ready to assist you with the development of your theme.
Make sure you review the Theme Review Guidelines before uploading a theme. If you have questions about these guidelines, you can ask them in the #themereview channel in Slack. Anyone with a WordPress.org account can access the Making WordPress Slack.
When you are ready to submit your theme for review, please upload your theme ZIP at Themes > Upload. Future updates are to be uploaded via the same page.
More information about the theme review process is available on the Themes Team website.