Whitewash is a mixture of white Portland cement and water. Don't use ordinary house paint. It can form a non-breathable film on your stucco, which will cause the paint to pop off when moisture migrates through the wall in the winter. Also, painted stucco needs costly sandblasting before redashing.
To make whitewash, mix white Portland cement (available at most lumberyards) and water in a pail to the consistency of pancake batter. Wet the stucco with a garden hose and apply the whitewash with a masonry brush or whisk broom. You can color the whitewash by adding masonry dye, which is available from brick suppliers. An exact color match is almost impossible, so plan to whitewash an entire wall for the best results.