Hydrogen burns with blue flame.Oxygen support burning when two atoms of Hydrogen combines with one atom of oxygen forms water this water put off the flames why?

This is an idiotic question. Drop your class quickly, if this is the norm.

when hydrogen reacts with oxygen, steam is formed, not water.

To put out the flame, either of the reactants has to be removed, which dousing with water will not accomplish, OR the sustaining temperature required for ignition has to be reduced, which water can do by cooling rapidly. But frankly, water would be hard pressed to put out a large size "fire" of H2 and O2, as it is an explosive mixture.

You might want to look at the fire triangle see http://en.wikipedia.org/wiki/Fire_triangle

if fuel, heat or oxygen is removed then a fire dies.

As Bob suggests removing the heat by dowsing with water will put out a fire. Although this is hard to do with a H2/O2 flame as the flame can still still be present underwater (see (Broken Link Removed)

Steam does have an effect on an H2/O2 mixture as it can have the effect of diluting the mixture below the explosive mixture (about 4% H2 in air)

When hydrogen burns with oxygen, a chemical reaction called combustion occurs. In this reaction, the hydrogen molecules (H2) combine with the oxygen molecules (O2) to form water (H2O). The process of burning hydrogen in the presence of oxygen releases a large amount of energy, which is expressed as a blue flame.

However, when the water is formed in the combustion process, it absorbs the heat from the flame and cools it down. This happens because the energy released during the combustion reaction is used to break the chemical bonds in the hydrogen and oxygen molecules, and then new bonds are formed to create water molecules. As a result, the heat that sustains the flame is dispersed into the surrounding water vapor, effectively extinguishing the flame.

So, the formation of water from the combination of hydrogen and oxygen not only consumes the gases involved in the combustion but also cools down the surrounding area, leading to the extinguishing of the flame.