.htaccess whacked!

I read something about being indexed good when I have set up my permalinks. So, I did. I created a file, paste the whole rewrite rule and unloaded it in my host.
I created a new post. When I clicked the title, I had the Bad Request 400 error. When I checked the contents of the archives folder, nothing is there.
And most of my links inside WP are whacked! Even when I click my Archive links, e.g. September, I have the same error also.
What is the problem there?