Homepage optimize?

I want to rank a keyword for my site, but I don't understand something here:1. I use thesis theme, question is that, do I need to link a main keyword post as my home page? 2. When bulding link, what we point the link to?, main keyword post or homepage?

If it's the main keyword dude, make it your homepage. Point your links to the homepage, and make posts relating to that keyword, with links to those posts on the homepage.

The reason for this, is because the SEO juice on the homepage will flow to the rest of the site, and end up building authority across the whole thing, as long as you've interlinked your pages and posts nicely.