When your basement (cellar) floods it is important that you act quickly. The sooner you address the problem the greater chance you have to minimize the damage. Water left in a basement can cause mold to grow and affect the top floors of your home.
Step 1: Make sure all electric is turned off before you walk into a flooded basement. (Call a professional basement waterproofing contractor)
Step 2: It is important to install a portable pump hooked up to a garden hose. (we call them floor suckers) It is better to remove the water from a flooded basement slowly rather than quickly. Removing water too quickly from the basement can cause structural damage to your foundation walls. There are also some pumps that sit outside the basement that run on gas and draw the water up from the basement.
Step 3: If you basement is finished it is important to call a professional basement drainage contractor as soon as possible to assess your basement and provide you with a permanent solution so your basement doesn't flood again. To find a reputable contractor visit http://www.basementdepot.com/
Step 4: Remove all organic materials that has gotten wet such as sheetrock, wood studs, carpeting, etc.
Step 5: DO NOT REFINISH YOUR BASEMENT WITH ORGANIC MATERIALS. Visit http://www.homebasementfinishing.com/ to learn how to finish a basement properly.
Step 6: Set up dehumidifier(s) to totally dry out your basement space. Keep running them until the relative humidity is below 50%. You can purchase a hygrometer (to measure the relative humidity) on http://www.basementdepot.com/ in the basement depot shopping mall.