Order of posts

Q: Displaying old posts then new post at main blog page how i can do this ?
A: If you wish to change the order of only 2 posts on your blog, change the date in "post options" for the second post, (intro to ISOSS"). e.g. Jan 25th 2010.
Publish post.
It will now appear on top of the other post dd Jan 24th 2010.
Problems may arise when you add a 3rd post tomorrow dd Jan 26th 2010. If will go to the top!

So, if you wish to have one particular post always showing first, you need to make it into a sticky post.
Go to your dashboard, edit post, post options.
Scroll down and change 25th Jan 2010 to a future date (25th Jan 2011)
Publish post. (This post will now stick to the top of your page until the future date).

Note: If you publish a new post with a future date, you have created a "scheduled post" and not a "sticky post". Your post will disappear and publish only on that date (2011).

If you are still unhappy and wish to add more posts below all existing posts, you can also do it.
Publish your 3rd post tomorrow (26/1/10); but edit/change the date to Jan 23rd 2010
For your 4th post, the date will have to be edited to Jan 22nd 2010 etc....
source: http://www.google.com/support/forum/p/blogger/thread?tid=213a62818636fc7c&hl=en&fid=213a62818636fc7c00047df46c738976