how can i walk in the water?

In water, there is an upthrust acting on your body due to buoyance of water. So the reaction by the floor on you is smaller and thus the friction between your foot and the floor. Due to the limited friction and the resistance from the water, you can only walk very slowly. You can walk a little bit faster if you can increase the friction between your foot and the floor by bearing additional weight.

Freeze the water.As it becomes ice,then you can walk on the ice.Of course,not in the water.When the ice of the surface gets melt,you can really walk in the water!

If you carry some lead bars on your body, you sink in water. You can walk IN water easily.

However, if you want to walk ON water, it's impossible.

See this fluid:
http://www.youtube.com/watch?v=f2XQ97XHjVw
http://en.wikipedia.org/wiki/Non-newtonian_fluid