Select the plus option on the Course Content page where you want your link to appear. Select create and then the Link option.
When you add a course link at the Course Content page, you can add course links to any content item.
Please follow the instructions on the following website for posting a web link in Bb:https://help.blackboard.com/Learn/Instructor/Ultra/Course_Content/Create_Content/Create_Course_Materials/Link_to_Websites
Select the Create Web Link tab to add a web link. Add a display name and paste the URL. When you are ready, select save.