Even if you have no curlers or curling iron, you can create waves with a flat iron. You'll need a small flat iron that has rounded or curved edges; a blunt edge will crease your hair. Using a flat iron won't give you ringlets but loose waves.
Heat your flat iron to a high setting.
Pin up the top section of clean, dry hair.
Grab a 1-inch section of hair. Place the heated flat iron in the middle of the section of hair at about a 45-degree angle then turn it in one and a half times in the direction of the curl you want with the hair still clamped in the iron.
Slowly pull the flat iron down the hair while it's still turned. Release it at the end. Repeat the 1-inch curling with the rest of your hair.
Finish with a lightweight hairspray.