Scoop up as much of the spill as possible, with a towel or a spoon.
 

Blot the spot, don't rub or scrub. Gently press clean cloths into the stained area to remove moisture. Scrubbing can damage the fiber and set the stain into the carpet.
 

Apply warm, not hot, water to the stained area and blot until the stain stops transferring to the cloth.
 

If you can still see the stain, make a Detergent Solution by adding 1/4 teaspoon dishwashing liquid to one cup warm water. Don't use too much soap, because it's difficult to rinse out of the carpet.
 

Apply the detergent solution, let sit five minutes, then rinse with clear warm water. Repeat until all the detergent is removed.
 

Place layers of white paper towels on the spill to absorb the liquid. Weight down the towels with a non-staining glass or ceramic object. You can let them sit overnight.
 

When the carpet is dry, vacuum to restore the texture.
 

If you can see the stain after all this, repeat steps 3 through 7. It means the stain penetrated deep into the pile and has wicked up to the surface.