Making the background of an image transparent

I don’t know if I’ll be able to word this correctly. I have an image with a logo in the middle and black colour all around. I want to make the black transparent. I don’t know how to utilize the alpha channel in this. Thanks.

Go into a program like GIMP or photoshop, and use the magic wand tool to select the black portion, then invert your selection, and paint the selection white. save it under another name. Now load your original image as a texture channel in blender, and then make another texture channel, and load the black and white one. Now down in the influence panel, un-check ‘color’ and check ‘alpha’. Now go to the materials panel and activate transparency, and turn the alpha slider all the way down.

Thank you for the replays. So whenever I want to make such a transparent image I’ll have to manually paint the alpha?