How to add “Make Homepage Button” in header

Well you could try thia:
http://www.addthis.com/#

But why not use some of the social bookmarking tools to publicize your posts instead? Such as Share This, Bookmarify, etc. There is no shortage of such plugins in the WP plugin repository.

Then you want this (but it’s so 1990s, IMHO!) 😀

http://www.htmlgoodies.com/beyond/dhtml/article.php/3470531