[black border around picture.]

Thanks everyone for your replies you don't know how much I appreciate it.

[black border around picture.]

I am trying to get a black border around a picture. I tried to use canvas to make a black border but when I fill it in with the paint bucket it darkens the whites in the picture. Is there something that you have to do to prevent this from happening. I also watched several tutorials on layers but I am totally lost. Thanks