First, wait a few minutes and try again.
Second, figure out whether Blackboard is down, or whether the problem is elsewhere – perhaps in your network connection. What about google.com? If you can't reach Google, then the problem is in your connection to the Internet and you should contact your personal Internet Service Provider.
→ If you're on campus and the wifi is down, please contact Technology Support to alert them to the problems.
If your wifi is working and you usually go to Blackboard through myUMBC, try going to https://blackboard.umbc.edu directly. It could be that myUMBC is having a problem but NOT Blackboard.