Blogging is very popular. Many people blog these days. WordPress is one of the most used blogging platforms there is. Make money by building custom WordPress themes!
What you need is your own domain name and hosting for using the WordPress platform. Look for a blog theme that is similar to your topic of choice.
There are really two ways to make money from this. For both of them your own website is required. The easiest way is offering different styles and themes that different bloggers may like and want to use. You can charge a fee for anyone who wants to download it and use the platform. If your design skills are good you can design custom themes and sell these to people.
Before doing this you need to be familiar with WordPress yourself. You can find information on how to build custom themes on the WordPress site itself and there are also a lot of different tutorials showing you step by step how to build custom themes,
covering all the design aspects you need to know.
It is useful to have knowledge of CCS and HTML, as that is used to customize the themes.
More information is available on the internet. This is just to give you an idea on how to creatively make money by building custom side themes! Also see: http://en.wikipedia.org/wiki/WordPress for information on WordPress.
Good luck with learning how to customize themes and sell to clients!