You can fly with different airlines to Bali. For example Cathay Pacific (stopover Hongkong), Malaysia Airlines (stopover Kualalumpur), Singapore Airlines (stopover Singapore) and KLM (stopover Singapore or Kualalumpur).
Booking of the tickets you can do yourself on the websites of the airline of your choice.

                 

       
You need a visa for entering Indonesia. When you stay no longer than 30 days you can get a visa on arrival at the airport Ngurah Rai in Denpasar or any other port of entrance.   
If you want to stay longer you need to get a visa at the Embassy of Indonesia in your own country.   

  
                 

Do not forget to ask your doctor or an health organisation in your surroundings what kind of vaccinations you need to have for your stay in Indonesia.