What is a blog used fo and how does it work?

At my kids school the parents always ask me for recipeis and for advice on kids. I have two very funny and accident prone, that makes for good advice.And not to toot my own horn the only things I am good at is my girls, (for now while there small, 4 and 6.That probably won't last very much longer.), and cooking. It is probably the only things I am good at. So they seem interested and that makes me flattered. So they asked me to start a blog and I have herd of them. I know that you talk about things on there so people can read it but how do I start and keep it updated. I did manage to find a few spots and followed the directions. After that I turned off my laptop and came back later and could not find it again. Could somebody take me step by step on what I need to start and how I can get in and out. Or maybe let me know if its even worth the time.