E. coli Test Method

I am a WASH ​manager in ​Pakistan and I ​would like to ​know how to ​properly ​conduct ​an  ​  Escherichia coli  test with the ​DelAgua kit (​Petri dish with ​an incubator) ​so we can check ​for  E. coli  in our water? Please share ​the complete ​methodology for ​the  E. coli  test.