I would like to learn about first aid skill. Can anybody suggest where is the right place to go?

Assuming you live in the United States the American Red Cross might be your best bet.

The Red Cross has certification programs for both first aid and CPR. They also have programs where you can train as a disaster relief worker.

You can also check out your local hospitals and health centers – a lot of the time they have classes (some official Red Cross classes, others just administered by the hospital). If you live in CA, or somewhere else with Kaiser Permanente, they have a great education program with loads of useful classes – and you can take classes there even if you’re not a member.

A good place to start would be to buy a Boy Scout Handbook. Most first aid and prevention (another type of first aid) is covered in this book.