Blogging has been going on for many years on the internet. It became popular for those who wanted to have a column/diary online...and has grown vastly. There are many web products that allow you to integrate a blog into your own web site or as a standalone blog.
Individuals use them as a daily record to keep their friends in the know
Experts use them to share their knowledge
Marketeers have use blogs to promote their businesses.
The key to a good blog is to make it interesting.
Saying what you had for dinner may not be interesting, but if you turn that into something like Jesse's Diet from the Fast Show you'll soon have your audience coming back for more.
Also talking about the latest gadget you bought may not appeal, but if you turn that into a review saying why you bought it what it does well and what's not good will gain you respect.
If you have a problem with your PC/camera/software moaning about it is fine, but saying how you fixed the problem will give others a reason to check out your latest tricks.
If you go on holiday write a diary of the days, add some local facts and people will come back for your guides.
Or just ramble on and amuse yourself (like I'm doing here
...blogging can be fun, but keeping up is the hard bit. I'm managing so far.