This study explores the dynamics within an online mental health community, specifically the r/MentalHealth subreddit, to understand user interactions and improve community effectiveness. Employing a methodology combining data crawling, topic modeling, toxicity analysis, and social network analysis, we analyzed 8,577 submissions from 7,562 users. Our findings reveal distinct subcommunities characterized by unique discussion topics, network positions, and contributions to toxicity. The study identifies four main user groups, each requiring tailored intervention strategies to enhance mental well-being and manage toxic behaviors. For example, techniques ranging from meditation and deep breathing for one subcommunity to cognitive-behavioral therapy and self-help resources for another are suggested based on their specific needs and dynamics. This research contributes to the broader field of digital mental health by providing actionable insights into fostering healthier, more supportive online environments for individuals discussing mental health issues.