Question

a picture of antimatter

Answer 1

you wont find much of a picture actually, so I had to use this image.
Antimatter is just opposite of matter, in charge, spin and other parameters. But these somehow cause the antiparticle to be same as the normal particle, in properties,  For example, a positron (the antiparticle of the electron) and an antiproton (the antiparticle of the proton) can form an antihydrogen atom.
The antihydrogen would have same properties as normal hydrogen and hence we can say that all antimatter would 'look' to us the same as normal matter.
Thats why, you wouldn't actually need a picture.