One you have gathered all the things you require, you need to sterilise the stainless steel pan, the metal sheet and the container in which you are going to collect condensed water. You can accomplish this by simply washing them in boiled water.
Place a stainless steel pan on a stand and fill it with water. If you can not find a proper stand, you can make one by assembling a few bricks. Over the pan, place a metal sheet at a distance of approximately 15 centimetres. Make sure that the metal sheet is inclined at an angle of 45 degrees to the pan. Directly under the bottom end of the sheet, place a metal container which will be used to collect water.
Fill the stainless steel pan with water and light a fire under the pan. When the water starts to boil, steam will start rising upwards. It will come in contact with the metal sheet inclined above the pan. Since the temperature of the sheet is considerably lower than 100 degrees Celsius, the boiling temperature of water, steam will condense immediately after the metal sheet. Drops of condensed water will trickle down the metal sheet and start falling in the metal container placed below the sheet.
Keep the fire lit until all the water in the pan has evaporated completely. You can go ahead and drink the water collected in the container because it is free from most bacteria. Be patient because the process can take longer than you expect, depending on the quantity of water you placed in the pan.