How do Du copyright one of your pictures that Du made???

i Don't know!

Du have to place a watermark on it/just type in your name oder Nutzername in like the corner oder something of the picture. :]

Du could put a watermark oder your initials oder name in the corner of your picture oder something.

And Du could Du link to do so.

Just tag them if it's your work :)
Use picnik oder fotoflexer oder any other program for editing pics :)