Create New Module or Activities in Moodle

http://docs.moodle.org/en/Development:NEWMODULE_Documentation#Getting_started

http://docs.moodle.org/en/Development:NEWMODULE_Tutorial

Use of Groups & Groupings

http://docs.moodle.org/en/Groupings#Enabling_the_use_of_groupings

Roles & Permissions in Moodle Administration

http://www.packtpub.com/article/roles-and-permission-moodle-administration-part1

Create own blocks in Moodle

http://docs.moodle.org/en/Blocks_Howto