For a newbie getting into online business would be somewhat difficult so better to start by building a site with unique concept with useful contents. Initially you should try to top SE so that your will get good organic traffic.
Once you get your site index and have a great traffic then you may consider signing up Adsense or some other ad revenue program. You can also sell ad space on your site and start earning
This is all about Advertising revenue, you can also use your site as an place to do business. If you have a good product/service which you think could be sell through web then all you have to do is to build a site around it, do SEO, market it properly and start earning
Before getting into any online business i will like to survey it and would like to get an rough idea of returns for my investment. For me web-hosting is the good business, you can get good returns for your investment if done properly.
Good service with affordable rates will attract more clients making your business a successful business.
If you are thinking of getting into hosting business then you can try
Reseller hosting from Webhosting.UK.com and start your own hosting business.