To upload an .srt file in Blackboard, goto My Media.  Next to the video you would like to add captions to, click the greyed out pencil highlighted below with the red arrow.

Screenshot of My Media showing greyed pen to click to edit media

You will then be on a screen with 9 options below your video, one of them is captions.  Click captions

screenshot showing details through replace video in media edit screen

You will now see a blue button on the far left, “upload caption file”, click it.

screenshot showing upload captions button

Then a new box will pop up.  Browse for the file.  Select the language.  And give it a label.  If the language is English, “English” would be a good label.  Then click save.

screenshot showing upload a captions file