Good for you for having an entrepreneurial curiosity! You are doing one of the most important first steps by just asking how and doing your research. There are several things you should consider - three of these are what your business will be, where it will be able to thrive, and what is needed to get it rolling.
What will your business be? It needs to be something you know how to do well and like doing. Something where you have the skills and expertise. It may require schooling or certification to learn the occupation or the trade. To be an owner and offer a business service to someone else, you will also need to be willing to dedicate a lot of time to doing this work. Until your business is up and thriving, which can take a long time, you have to be willing to put in the hours and the good old fashioned elbow grease to get the work done in addition to managing the business aspect of it. Make sure you have a passion for your chosen field as well as an expert level of knowledge.
Where will it thrive? Once you know what you want to do, it's important to understand where you can do it successfully. As an example, if you want to open a dry cleaning service, you have to fill a need for the service. If there are 2 other dry cleaners in your neighborhood, you may have to go to another area where they don't have as much access to dry cleaning services in order to fill a need. In addition to finding a community where the service is needed, you have to consider where you can go to grow that business over time.
What do you need to get it rolling? After you have a business concept and a target market, you will need financial support. The best way to get financial support is to have a good solid business plan that allows you to secure a loan or other financing support, like an investor. The strength of your business plan will help determine what financial support is available to you. There may even be grant money available.
A good way to work through all of these things is to partner with your local Small Business Administration or a Small Business Incubator. These are organizations that are designed to help new business ventures get started - working through business plans, helping identify target markets, etc. and may even be aware of areas that cater to building new business. there is also a lot of research that you can do on-line about how to start up a business.
Find your passion first, then follow your dreams. You can do anything you set your mind to do! Good luck.