According to the powers that be at Facebook you can only boost a Facebook post from your Facebook page and not from your personal profile.
To boost posts on your page;
1) Go to a post you have created and click Boost Post button in the lower right corner of your post.
2) Choose your audience and budget based on how many people you want to reach and how long you'd like your boost to run. You can also change your payment method.
3) (So basically once your payment and audience have been setup) click Boost Post