wtp peace

how do I i do a graphic or gif or photo where the back ground is invisible?

You know like how for example in my little slick rick thing in my sig, how do I do it so the pic ends at the borders of his body? I dotn want that black background behind it.

So i just want to cut things out, i dont want square or rectangle pics all the time, just the outline that i want. I always wanted to know this.