The online group is definitely a good idea. Promote your group through different platforms (Facebook, Twitter, on blogs, etc.) and get the news out about your LGBTQ organization. But first, you should probably have a small committee to help you run the group. They can be friends or classmates, but whoever they are, they can help generate ideas and fundraisers and make posters. Once you have your committee, take your group idea to your guidance counselor at school or your vice-principal/principal to have your group approved as a school club. That way, you can build up your organization and recruit new members. Make posters and post them around your school to, again, promote your club, make weekly or daily announcements and hold weekly meetings to discuss goals, problems and just to have fun! Good luck with your LGBTQ group!