What kind of online business I prefer ?

There is a lot of different ways to make money on the Internet. You can put in your site some products of other companies and to promote them. You can also install a search box, that will redirect your visitors to some sponsored links. There is an option to put sponsored link directly in your content and to earn money when somebody click on it.
All of this methods to start online business are profitable, but some of them are useful if you already have a web site with lots of visitors every day.
So I recommend if you haven't web site like this and you need to start from the beginning.
The easiest way to lunch your online business is to use one (or more then one) systems for sponsored content - sponsored links like Google Adsense.
What can you do?
You can lunch your own Internet directory with lots of sub categories. There you need to collect and post web sites. This is the easiest way to start online business, because the content of the site depends only of you. I mean that if you have free time to collect and post web sites in your category, your site will grow up to large Internet database of web sites.
Another priority to do this kind of web sites is the targeting of your visitors. For example if you have a web directory consisted of cars web sites, you will have visitors that search web sites about cars. So if you install then Google Adsense in each of sub categories your visitors will start making a lots of money for you.
How to start?
First you'll need a domain name and hosting. This is absolutely not expensive.
Next you'll need a web directory script. I recommended this one. It is very sample to use and SEO optimized
You can learn more about how to make money from here
Good luck!