Materials Needed:

Scissors
Tape
Fishing Line (or any type of string you want)
Small binder clips/ butterfly clips (Clothes pins would work as well)
"Eye" Hooks
Card Stock
Picture(s) you want to hang up

Step 1: Step One: the Picture

Clip one of the binder clips to a piece of card stock. (Pic 1)

Cut the paper where the clip ends, so you get what you see in Pic 2
Make sure the cardstock is long enough to fit on the back of your picture.

Put the binder clips and card stock on the back of your picture, and tape it close to the middle. (Pic 3)

You should now be able to hold the picture by just holding the clip.

Step 2: Step 2: the Wall

BEFORE YOU DO THIS STEP, ASK PERMISSION TO PUT HOLES INTO YOUR WALL

Find a wall where you want to put your pictures. (Pic 1)

Figure out where you want your first (or only) string, mark it with a pencil. (Pic 2)

Take one of the eye hooks and screw it into the wall at the mark. (Pic 3)
It is okay if it doesn't go through all of the drywall, mine didn't and it can hold over six pictures.

Measure the height of your eye hook if you haven't already. (Pic 4)

Measure to that height on the other side of the wall and mark that point (Pic 5)
Screw in the other eye hook.

Tie some fishing line to one of the eye hooks. (Pic 6)

Roll out the fishing line until you get to the other eye hook, then roll out some extra. Tie the end to the other eye hook, tightly.
You will have excess line, so cut it off. (Pic 7,8,9)

You now have completed the holder for the pictures. (Pic 10,11)

Step 3: Step 3: Finishing

Clip the binder clip onto the fishing line, it's okay if it drops a bit. (Pic 1, 2)

Add your other pictures to the line. (Pic 3)

And add more lines if you want. (Pic 4)

You're done.