This is very easy to do and tastes yummy:
take a cup of whole almonds, non-roasted or salted and soak them for 24 hours, then rinse. At this stage the almonds make a great snack, but refrigerate or else they rot.
take a handful of dried raisins and soak for 2 hours,
put almonds and raisins in the blender, fill up with water and i usually add maple syrup or honey for more sweetness, but for most people the raisins are just fine.
Blend, then strain with a fine strain, keep the pulp for cookies or cake.. and voila, you've got yummy almond milk that can refrigerate in your fridge.
I usually use organic almonds and purified water, but whatever suits you best!