These tips may help the shy student to feel more confident. Practice replacing your self-critical thoughts with more supportive ideas. At the next class session repeat this process with the same person and include an additional classmate in the conversation. Keep repeating the process until a handful of people start to feel more familiar to you and it seems more natural to talk to them. A next logical step would be to get some of them together for study or recreation.
Nothing helps people get to know each other better than working on a common project together.
Frequent eye contact is essential in modern communication. A relaxed, but alert posture is more approachable than a rigid one. If you have a specialized interest, learn to talk about it so that beginners as well as experts can understand you. Collect amusing stories or jokes to tell. Give compliments when appropriate.