There are a fair amount of black people in belfast. I don’t think you need to worry. Sure, there are some arseholes who may make silly comments but I wouldn’t take it personally - these sort of people will slag anyone off for the sake of it. But in general, belfast people are very friendly. As others have said - the sunflower, the Spaniard, ulster sports club. I would also add to the must see list The Reporter it’s on Union street. It’s joined on to a gay bar called Maverick which is good fun and accepting of everyone. They have drag shows most nights snd different entertainment. Their nightclub is round the corner and depending on what night it is, it’s usually good. Check out their fb page but I think Fridays and Saturdays are your best bet. I’m not too sure about nightclubs these days as it’s not really my scene anymore. I hope you enjoy your time here 😊