How do I start a blog that anyone can post to?

I need to know the software or blog site to use so that any reader can post comments to my blog. I am a rank beginner at blogging, so need any info! Thanks!

It sounds like you're trying to start a wiki instead of a blog. Wetpaint has them. Be forewarned, the free wikis may have inappropriate ads, so if you're not looking to have strange ads running alongside your material, you may have to pay a little money.