That does not look like .htaccess file rules produced by WordPress 2.x. Copying from someone elses file is probably producing a conflict.
WordPress can create the .htaccess rules for your permalink structure if it can write to the file, I suggest you check the permissions on the file and remove the code you inserted.
Your question is not clear but I will have a go at answering.
If you mean how do you remove the ‘hello world’ post from the blog home page ….
1. it will be replaced by new content as you add it or
2. just delete it
If you mean how to change the content on the home page to be things other than posts ….
check out http://codex.wordpress.org/Pages#Using_a_Page_as_the_Front_Page and the advice on creating a static front page.
