How to have a particular post, first to be displayed at the home page always in BlogSpot

First go to the page you want to be displayed always at the homepage. Then edit the post.
When you are editing your post, click on the post options in the bottom of the compose page that is the edit page.
In the Post options you will be able to see post date and time, text box available. In the date field type a date which is in the future so that, that particular post will be displayed first even though you post after it.