Answer:

The biggest concern will be removing as much of the large debris as possible so as not to strain/clog/contaminate your filter and pump. Once the large debris is gone, top up the water, turn on the pump/filter and get it balanced (pH, alkalinity and hardness). Then start adding algaecide if any green color to the water and chlorine (be carefull to follow instructions carefully for algaecide as it may go in particular order with your chlorine) to start to clear up and rid the pool of contaminants. The water balance and filtering should clear it up, but it is not a particularly quick process. It may take a few days to clear up from this point. If it is not improving daily, you should check the filter. It may need to be cleaned or not getting enough pressure, etc. Proper filtration along with the chemical treatments is the key to your recovery.