If you are asking from a technical perspective, then starting a business is as simple as giving your business a name and registering it at your local business registrar. In Singapore, we register businesses through ACRA.
If your question is what it takes for your business to be successful, then I will break it down in to several aspects.
First of all, you need to have the passion. You need to have the passion for what you plan to start. Without passion, you will be drained very soon. This is especially so if your business does not start making money fast enough.
Next, you need to have the vision. What is the problem which your business is trying to solve? Is it addressing a niche market? Are you able to deliver the same products/services better, faster or cheaper? If you have no answers to these questions, then your business will most likely fail.
Finally, the right people. Do you have a team of trustworthy people who share your passion or believe in your vision? You can never start a successful business alone, it's always a team effort.
So before you start, ask if you have the passion, vision and right team. With all these 3 elements, I think you will be able to build something great! Wish you all the best if you intend to start one!