The User Guide contains an introduction, tutorial, a number of "how to" guides, and then reference documentation for the components that make up the framework. Check the User Guide !
CodeIgniter is a community-developed open source project, with several venues for the community members to gather and exchange ideas. View all the threads on CodeIgniter's forum, or chat on Slack !
CodeIgniter is a community driven project and accepts contributions of code and documentation from the community. Why not join us ?