Are you prepared to commit the amount of time needed for such an undertaking? Before doing so, be sure to read about the ethical issues and safety concerns.
Blogging can be great! It connects teachers, creates discussion, and helps you to think outside of the box. If you've never done it before, I'd start by setting up a basic website from an easy-to-use platform. (There are free and premium sites you can use, a short Google search should help you find what you need.) Then I'd look into other teacher bloggers to see how they write and how they use blogging with their classes (since it sounds like you're interested in that). You can even look up teachers who blog by subject and grade. I'd love to see it once it's up!