Talk to your classmates about the kinds of online channels they use to communicate with other students. Some educational institutions provide message boards per class or professor where students can post questions and answers to classroom material.
Join the group, message board, social media outlet or email list that your classmates utilize most for exchanging information and classroom material. Send an introductory email, introducing yourself and your academic strengths, to show your desire and ability to contribute to the group.
Get comfortable with the most used online channel so that posting responses to questions, notes and other materials is quick and easy for you. Read past questions and answers and notice how material is shared or uploaded to understand how to contribute most productively.
Keep your notes well organized and legible if handwritten so that making copies can be done efficiently if requested by a classmate.
Check the online channel daily for questions or requests by classmates and post a response if you are confident in your ability to provide an answer. Never offer an answer about material you don't fully understand as you may end up giving false information.
Follow up with classmates after you have supplied answers or material. Keep a direct connection with individual classmates to allow you to receive faster response time to your own questions and material requests.