Flirt with him first and see whether how he responds. Watch his nonverbals as well as paying attention to his verbal responses. This should give you an indication as to whether he sees you more of a buddy or a potential dating partner. If things go well, share your social media and other contact information and take the conversation online via text and phone in addition to in-person so you can deepen your connection more than just sitting beside one another. Is your online or text communication with him generally one-way or mutual? Pay attention to that. If it's going well, compliment him, tell him he is special, or what you like about him and see how he responds. This should help you communicate your interest. Pay attention to his cues. Remember: you shouldn't do all the relationship work!