What license should I choose for a GitHub repository?

As a best practice, we encourage you to include the license file with your project.

I don’t understand licensing as much, and for other projects (other than web development), I’ve gone with MIT. Taking into account, that everything isn’t exactly mine; I’ll be using a CSS framework, a PHP framework, etc.

You’re under no obligation to choose a license. However, without a license, the default copyright laws apply, meaning that you retain all rights to your source code and no one may reproduce, distribute, or create derivative works from your work. If you’re creating an open-source project, we strongly encourage you to include an open-source license.

Licensing a repository:

Public repositories on GitHub are often used to share open-source software. For your repository to truly be open source, you’ll need to license it so that others are free to use, change, and distribute the software.

Applying a license to a repository with an existing license:

The license picker is only available when you create a new project on GitHub. You can manually add a license using the browser. For more information on adding a license to a repository, see “Adding a license to a repository.”