Pepper your speech with the highlights of the forthcoming program. If you are not the organiser of the Black History Program, then find out who is and ask them about what the day will entail. Try to think about who will be in the audience and what you remember from attending previous Black History Programs whether at this church of other churches.
That doesn’t mean they cannot be memorable, but you must always bear in mind that you are there to welcome people to the church, maybe people who haven’t been to a church for a while so it also needs to be friendly as well as informative. Welcome speeches by their very nature are meant to be short, sharp and functional.