Step 1
Empty the mix* on a flat clean surface and form a depression in the middle of the mix.
*The concrete mix would generally be conformed of 1 part cement, 3 parts sand, and 3 parts aggregate or stone. The mix ratio may vary from region to region due to differences in the components.
Step 2
Measure the recommended water amount (each 80-pound bag of concrete mix will require about 3 quarts of water).
Step 3
Pour approximately 2/3 of the water into the depression.
Step 4
Work the mix with a shovel, gradually adding water, until the mix reaches a uniform, workable consistency. Properly mixed concrete should look like thick oatmeal and should hold its shape when it is squeezed in a gloved hand.
NOTE: the more water that is added to the mix the weaker it becomes; adding one extra quart of water per 80 lb bag can reduce the strength of the concrete by up to 40%.
Source: http://www.quikrete.com/athome/video-mixing-concrete-hand.asp