If you do not have a handheld milk frother, you have a few different options.  Option 1: Place warm milk into a blender and blend until doubled in size.  Option 2: Place warmed milk into a large jar, seal the lid tightly, and shake until the volume has increased (shaking vigorously for about 1 minute). Option 3: Warm your milk on the stove over medium heat until starting to steam (do not boil!). Turn off the stove and whisk until frothy.