MG 2.1 How can I create a tag in My Album within the Media gallery?

I cant see how to create a tag for a photo I have uploaded in my own Album (within Media).
Any clues please - is there a video to show this being done?
Regards & thanks, Mike
Somewhat amazed to have no response the above question! Sadly this does not seem to be an active community hep forum:(
Anyway I have finally found there was a setting in the admin section that needed to be changed. It was in setup>options>content tagging - but that was only accessible through in the tiny gearwheel in the top right corner of the admin screens!
Hope this helps someone else:)