What is a blog ?
A blog or weblog is a journal (or newsletter) that is frequently updated and intended for general public consumption. Blogs generally represent the personality of the author or the Web site.
Why get one ?
Well everybody has one (I just got mine) and some people make money on them, so why don't you just get yourself one. You can setup one for free with blogger or wordpress (the 2 most popular ones) and start putting your ideas down. You don't have to pay for hosting nor for a domain, its completely free.
How do you make money from a blog ?
Well the basic idea is simple, you write about your favorite topic and if you have some passion you get enough people to read your blog and hopefully click on the ads that are in your blog pages.
What ads ?
Most people have ads on their blogs (just look on the top and right side), so they can make a little money to support their passion which is writing about their favorite topic. Some people make decent money because they attract a big audience and a lot more people get to click on the ads.
How do you get money from ads ?
Well when people click on the ads the click is counted automatically from your ad provider and it is translated into a few cents (or a few bucks depending on the topic). When you reach a certain amount you can collect the money.
How do I get ads on my site ?
The most well know ad provider is google with their adsense program. This is a PPC (pay per click) program that means that you get paid only if someone clicks on your ads. They have wizards to help you setup the ads and give you instructions on how to include them on your pages, so it has become pretty easy to set up a blog to display ads.
So to round this up, find a topic, get a blog, and register with an ad provider. Chances are that you already have some sort of account with Google, probably gmail so just go to adsense and setup up your publisher's account. Then go to blogger (same as blogspot - part of the google services) and setup your blog. If you get into trouble post a comment here and I will try to help on the technical aspects.
What is a blog ?