Pearl Beads (These can be as cheap as you like, you can't tell once it's all finished)
A Spool (you won't use it all) Satin Ribbon
(In a width that's fairly close to the width of the pearls)
Needle and Thread
Thread your thread into the needle
Leaving about 6-8 inches for a tail, place needle through the middle of the ribbon from bottom to top, not pulling the needle out.
Put a pearl on your needle, then feed the needle and thread through. Then tie a knot with the ribbon and the thread, to keep the necklace secure.
You may need to look at the picture to do this step, as it may be hard to fully explain. But you then fold the top of the ribbon back over the pearl (making a "c" with the ribbon), and push needle through in the middle of the ribbon where it hits the top of the pearl.
(Sorry, this was really hard to photograph one-handed, so it's not exactly how I explained, but hopefully you can look at it, and follow the thread to see what I'm talking about.)
Repeat these steps over and over and over until your necklace is the length you want.
Tie off both ends of the necklace in a knot for safe keeping. Tie the two ends together in a bow, and your necklace is officially done!
P.S. I like to burn the ends of the ribbon to seal them so they don't fray, but you don't absolutely have to.